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- Fullerenes in the circumstellar medium of Herbig Ae/Be stars: insights
from the Spitzer mid-infrared spectral catalog-
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Pages: 1601 - 1613
Abstract: ABSTRACTThis study presents the largest mid-infrared spectral catalogue of Herbig Ae/Be stars to date, containing the Spitzer Infrared Spectrograph spectra of 126 stars. Based on the catalogue analysis, two prominent infrared vibrational modes of C60 bands at 17.4 and 18.9 μm are detected in the spectra of nine sources, while 7.0 μm feature is identified in the spectra of HD 319896. The spectral index analysis and the comparison of the known sources with C60 features indicated that there exist two different types of emission classes among the sample of stars. The infrared spectra of six Herbig Ae/Be stars in this study resemble that of reflection nebulae, and their association with previously known reflection nebulae is confirmed. In the case of three Herbig Ae/Be stars, we report the tentative evidence of C60 emission features originating from the circumstellar disc or nearby diffused emission region. The detection fraction of C60 in the total HAeBe star sample is ∼7 per cent, whereas the detection fraction is 30 per cent for HAeBe stars associated with nebulosity. In the catalog, C60 is exclusively present in the circumstellar regions of B type Herbig Ae/Be stars, with no evidence of its presence detected in stars with later spectral types. The present study has increased the number of young stellar objects and reflection nebulae detected with C60 multifold, which can help in understanding the excitation and formation pathway of the species.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1511
Issue No: Vol. 523, No. 2 (2023)
- The shape of dark matter haloes: results from weak lensing in the
ultraviolet near-infrared optical Northern survey (UNIONS)-
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Pages: 1614 - 1628
Abstract: ABSTRACTCold dark matter haloes are expected to be triaxial and so appear elliptical in projection. We use weak gravitational lensing from the Canada–France Imaging Survey (CFIS) component of the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS) to measure the ellipticity of the dark matter haloes around Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey Data Release 7 (DR7) and from the CMASS and LOWZ samples of the Baryon Oscillation Spectroscopic Survey (BOSS), assuming their major axes are aligned with the stellar light. We find that DR7 LRGs with masses M ∼ 2.7 × 1013 M⊙ h−1 have halo ellipticities e = 0.46 ± 0.10. Expressed as a fraction of the galaxy's ellipticity, we find fh = 2.2 ± 0.6. For BOSS LRGs, the detection is of marginal significance: e = 0.20 ± 0.10 and fh = 0.7 ± 0.7. These results are in agreement with other measurements of halo ellipticity from weak lensing and, taken together with previous results, suggest an increase in halo ellipticity of 0.10 ± 0.06 per decade in halo mass. This trend agrees with the predictions from hydrodynamical simulations, which find that at higher halo masses, not only do dark matter haloes become more elliptical, but that the misalignment between the major axis of the stellar light in the central galaxy and that of the dark matter decreases.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1519
Issue No: Vol. 523, No. 2 (2023)
- Evolution and explosions of metal-enriched supermassive stars: proton rich
general relativistic instability supernovae-
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Pages: 1629 - 1640
Abstract: ABSTRACTThe assembly of supermassive black holes poses a challenge primarily because of observed quasars at high redshift, but additionally because of the current lack of observations of intermediate mass black holes. One plausible scenario for creating supermassive black holes is direct collapse triggered by the merger of two gas-rich galaxies. This scenario allows the creation of supermassive stars with solar metallicity. We investigate the behaviour of metal enriched supermassive stars which collapse due to the general relativistic radial instability during hydrogen burning. These stars contain both hydrogen and metals and thus may explode due to the CNO cycle (carbon–nitrogen–oxygen) and the rp process (rapid proton capture). We perform a suite of stellar evolution simulations for a range of masses and metallicities, with and without mass-loss. We evaluate the stability of these supermassive stars by solving the pulsation equation in general relativity. When the stars becomes unstable, we perform 1D general relativistic hydrodynamical simulations coupled to a 153 isotope nuclear network with cooling from neutrino reactions, in order to determine if the stars explode. If the stars do explode, we post process the nucleosynthesis using a 514 isotope network which includes additional proton rich isotopes. These explosions are characterized by enhanced nitrogen and intermediate mass elements ($16\ge \rm {A}\ge 25$), and suppressed light elements ($8\ge \rm {A}\ge 14$), and we comment on recent observations of super-solar nitrogen in GN-z11.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1522
Issue No: Vol. 523, No. 2 (2023)
- Black hole feeding and feedback in a compact galaxy
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Pages: 1641 - 1647
Abstract: ABSTRACTWe perform high-resolution hydrodynamical simulations using the framework of MACER to investigate supermassive black hole (SMBH) feeding and feedback in a massive compact galaxy, which has a small effective radius but a large stellar mass, with a simulation duration of 10 Gyr. We compare the results with a reference galaxy with a similar stellar mass but a less concentrated stellar density distribution, as typically found in local elliptical galaxies. We find that about 10 per cent of the time, the compact galaxy develops multiphase gas within a few kpc, but the accretion flow through the inner boundary below the Bondi radius is always a single phase. The inflow rate in the compact galaxy is several times larger than in the reference galaxy, mainly due to the higher gas density caused by the more compact stellar distribution. Such a higher inflow rate results in stronger SMBH feeding and feedback and a larger fountain-like inflow-outflow structure. Compared to the reference galaxy, the star formation rate in the compact galaxy is roughly two orders of magnitude higher but is still low enough to be considered quiescent. Over the whole evolution period, the black hole mass grows by ∼50 per cent in the compact galaxy, much larger than the value of ∼ 3 per cent in the reference galaxy.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1529
Issue No: Vol. 523, No. 2 (2023)
- Multifrequency analysis of the radio emission from a post-merger galaxy
CGCG 292-057-
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Pages: 1648 - 1660
Abstract: ABSTRACTGalaxies exhibiting a specific large-scale extended radio emission, such as X-shaped radio galaxies, belong to a rare class of winged radio galaxies. The morphological evolution of these radio sources is explained using several theoretical models, including galaxy mergers. However, such a direct link between a perturbed radio morphology and a galaxy merger remains observationally sparse. Here, we investigate a unique radio galaxy J1159+5820, whose host CGCG 292-057 displays the optical signature of a post-merger system with a distinct tidal tail feature, and an X-shaped radio morphology accompanied by an additional pair of inner lobes. We observed the target on a wide range of radio frequencies ranging from 147 to 4959 MHz, using dedicated GMRT and VLA observations, and supplemented it with publicly available survey data for broad-band radio analysis. Particle injection models were fitted to radio spectra of lobes and different parts of the wings. Spectral ageing analysis performed on the lobes and the wings favours a fast jet realignment model with a reorientation time-scale of a few million years. We present our results and discuss the possible mechanisms for the formation of the radio morphology.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1533
Issue No: Vol. 523, No. 2 (2023)
- Synchrotron emission from double-peaked radio light curves of the
symbiotic recurrent nova V3890 Sagitarii-
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Pages: 1661 - 1675
Abstract: ABSTRACTWe present radio observations of the symbiotic recurrent nova V3890 Sagitarii following the 2019 August eruption obtained with the MeerKAT radio telescope at 1.28 GHz and Karl G. Janksy Very Large Array (VLA) at 1.26−35 GHz. The radio light curves span from day 1 to 540 days after eruption and are dominated by synchrotron emission produced by the expanding nova ejecta interacting with the dense wind from an evolved companion in the binary system. The radio emission is detected early on (day 6) and increases rapidly to a peak on day 15. The radio luminosity increases due to a decrease in the opacity of the circumstellar material in front of the shocked material and fades as the density of the surrounding medium decreases and the velocity of the shock decelerates. Modelling the light curve provides an estimated mass-loss rate of ${\overset{\hbox{$\bullet $}}{M}}_{\textrm {wind}} \approx 10^{-8}\, {\textrm {M}}_\odot ~{\textrm {yr}}^{-1}$ from the red giant star and ejecta mass in the range of Mej = 10−5––10−6 M⊙ from the surface of the white dwarf. V3890 Sgr likely hosts a massive white dwarf similar to other symbiotic recurrent novae, thus considered a candidate for supernovae type Ia (SNe Ia) progenitor. However, its radio flux densities compared to upper limits for SNe Ia have ruled it out as a progenitor for SN 2011fe like supernovae.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1534
Issue No: Vol. 523, No. 2 (2023)
- A small survey for massive stars in the LMC/SMC: binaries and pulsations
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Pages: 1676 - 1698
Abstract: ABSTRACTBinarity and pulsations are two notable properties that frequently appear together in massive stars. To place constraints on how binarity affects stellar evolution, the exact parameters of massive stars in binary systems must be known. Their exact and accurate masses and radii, which were calculated from binary dynamics, present model-independent restrictions and challenge existing theories of stellar evolution. In this investigation, our goal is to determine the atmospheric characteristics of nine double-lined spectroscopic binaries that are located in the Large Magellanic Cloud and Small Magellanic Cloud. Nine newly discovered double-lined eclipsing binaries with B-type massive components have been studied; these binaries were found using the OGLE variable star catalogues. The absolute physical parameters of each component have been measured with an accuracy of less than or equal to 3 per cent. By analysing through Transiting Exoplanet Survey Satellite data of the systems, we were able to identify five candidates for slowly pulsating B stars in massive binary systems with masses ranging from 2 to 25 M⊙. According to the results of the preliminary research, the orbital periods of these binary systems span anywhere from 1.8 to 6.3 d, whereas the pulsating periods range anywhere from 0.3 to 1.5 d. The achievement in identifying a significant number of pulsating eclipsing systems opens the door to the initial sensible approach of constraining the internal physics of a group of massive stars via asteroseismology of eclipsing binaries including such stars.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1541
Issue No: Vol. 523, No. 2 (2023)
- Analyses of overlapping gravitational wave signals using hierarchical
subtraction and joint parameter estimation-
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Pages: 1699 - 1710
Abstract: ABSTRACTIn the coming years, third-generation detectors such as Einstein Telescope and Cosmic Explorer will enter the network of ground-based gravitational-wave detectors. Their current design predicts a significantly improved sensitivity band with a lower minimum frequency than existing detectors. This, combined with the increased arm length, leads to two major effects: the detection of more signals and the detection of longer signals. Both will result in a large number of overlapping signals. It has been shown that such overlapping signals can lead to biases in the recovered parameters, which would adversely affect the science extracted from the observed binary merger signals. In this work, we analyse overlapping binary black hole coalescences with two methods to analyse multisignal observations: hierarchical subtraction and joint parameter estimation. We find that these methods enable a reliable parameter extraction in most cases and that joint parameter estimation is usually more precise but comes with higher computational costs.
PubDate: Tue, 23 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1542
Issue No: Vol. 523, No. 2 (2023)
- Sustained super-Eddington accretion around neutron stars &
black holes-
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Pages: 1711 - 1717
Abstract: ABSTRACTRecently, it was shown that the formation of a photon-trapping surface might not be sufficient to ensure unimpeded super-Eddington (SE) accretion. In light of this finding, here we derive a condition such that sustained and unimpeded SE accretion could be achieved in optically thick slim accretion discs surrounding neutron stars (NSs) and black holes (BHs). For this, we calculate a semi-analytic approximation of the self-similar global radial velocity expression for an advection-dominated flow. Neglecting the influence of relativistic jets on the accretion flow, we find that for Eddington fraction $\dot{m} \gtrsim 1.5 (\epsilon /0.1)^{3/5}$ (ϵ being the accretion efficiency) sustained SE accretion might be possible in slim discs around BHs irrespective of their spin. The same condition holds for NSs when ϵ ≳ 0.03. The presence of a surface magnetic field might truncate the disc at the magnetosphere of the NS, resulting in lower efficiencies and consequently changing the condition to $\dot{m} \gt 0.013 \epsilon ^{-19/31}$. Our approach suggests that sustained SE accretion might almost always be possible around NSs and BHs hosting accretion discs.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1558
Issue No: Vol. 523, No. 2 (2023)
- A test of invariance of dark matter halo surface density using
multiwavelength mock galaxy catalogues-
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Pages: 1718 - 1727
Abstract: ABSTRACTA large number of observations have shown that the dark matter halo surface density, given by the product of halo core radius and core density, is nearly constant for a diverse suite of galaxies. Although this invariance of the halo surface density is violated at galaxy cluster and group scales, it is still an open question on whether the aforementioned constancy on galactic scales can be explained within Lambda cold dark matter (ΛCDM). For this purpose, we probe the variation of halo surface density as a function of mass using multiwavelength mock galaxy catalogues from ΛCDM simulations, where the adiabatic contraction of dark matter haloes in the presence of baryons has been taken into account. We find that these baryonified ΛCDM haloes were best fitted with a generalized Navarro–Frenk–White profile, and the halo surface density from these haloes has a degeneracy with respect to both the halo mass and the virial concentration. We find that the correlation with mass when averaged over concentration is consistent with a constant halo surface density. However, a power-law dependence as a function of halo mass also cannot be ruled out.
PubDate: Fri, 12 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1427
Issue No: Vol. 523, No. 2 (2023)
- Correction to: The X-ray variation of M81∗ resolved by Chandra and
NuSTAR-
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Pages: 1728 - 1728
Abstract: This is a correction to: Shu Niu and others, The X-ray variation of M81∗ resolved by Chandra and NuSTAR, Monthly Notices of the Royal Astronomical Society, Volume 522, Issue 2, June 2023, Pages 2644–2654, https://doi.org/10.1093/mnras/stad1080.
PubDate: Tue, 30 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1538
Issue No: Vol. 523, No. 2 (2023)
- The LOFAR Two-metre Sky Survey: Deep Fields data release 1. V. Survey
description, source classifications, and host galaxy properties-
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Pages: 1729 - 1755
Abstract: ABSTRACTSource classifications, stellar masses, and star-formation rates are presented for ≈80 000 radio sources from the first data release of the Low Frequency Array Two-metre Sky Survey (LoTSS) Deep Fields, which represents the widest deep radio survey ever undertaken. Using deep multi-wavelength data spanning from the ultraviolet to the far-infrared, spectral energy distribution (SED) fitting is carried out for all of the LoTSS Deep host galaxies using four different SED codes, two of which include modelling of the contributions from an active galactic nucleus (AGN). Comparing the results of the four codes, galaxies that host a radiative AGN are identified, and an optimized consensus estimate of the stellar mass and star-formation rate for each galaxy is derived. Those galaxies with an excess of radio emission over that expected from star formation are then identified, and the LoTSS Deep sources are divided into four classes: star-forming galaxies, radio-quiet AGN, and radio-loud high-excitation and low-excitation AGN. Ninety-five per cent of the sources can be reliably classified, of which more than two-thirds are star-forming galaxies, ranging from normal galaxies in the nearby Universe to highly-starbursting systems at z > 4. Star-forming galaxies become the dominant population below 150-MHz flux densities of ≈1 mJy, accounting for 90 per cent of sources at S150MHz ∼ 100 μJy. Radio-quiet AGN comprise ≈10 per cent of the overall population. Results are compared against the predictions of the SKADS and T-RECS radio sky simulations, and improvements to the simulations are suggested.
PubDate: Sat, 29 Apr 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1308
Issue No: Vol. 523, No. 2 (2023)
- Mid- and far-infrared spectroscopy of nucleobases: molar extinction
coefficients, integrated molar absorptivity, and temperature dependence of
the main bands-
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Pages: 1756 - 1771
Abstract: ABSTRACTThe nucleobases, namely the purines adenine and guanine and the pyrimidines cytosine, thymine, and uracil, are the key monomers of the information polymers DNA and RNA. All the nucleobases were recently detected in the analysis of certain meteorites known as carbonaceous chondrites. The concentration of the nucleobases found in meteorites is smaller than the concentration of amino acids. However, the nucleobases were successfully synthesized abiotically by ultraviolet irradiation of interstellar ice analogues at 10 K. Consequently, it is possible that the purines and pyrimidines may be present in the interstellar medium or in other space environments and may be detectable by the new orbiting telescopes that indeed are able to cover not only the mid-infrared spectral range but also the far-infrared. This work supplies the reference spectra of the five nucleobases used by the terrestrial biochemistry in the mid-infrared and in the far-infrared with the purpose to facilitate the search and identification of these astrobiological and astrochemical relevant molecules in space. The mid-infrared spectra of all nucleobases were recorded at three different temperatures from −180 °C to nearly ambient temperature and at +250 °C. Furthermore, the molar extinction coefficients (ε) of all mid- and far-infrared bands were determined, as well as the integrated molar absorptivities (ψ). With the reported infrared spectra together with the ε and ψ values, it will be possible to identify qualitatively the nucleobases and estimate their relative abundance in space.
PubDate: Tue, 09 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1367
Issue No: Vol. 523, No. 2 (2023)
- Photometric IGM tomography with Subaru/HSC: the large-scale structure of
Ly α emitters and IGM transmission in the COSMOS field at z ˜ 5-
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Pages: 1772 - 1798
Abstract: ABSTRACTWe present a novel technique called ‘photometric IGM tomography’ to map the intergalactic medium (IGM) at z ≃ 4.9 in the COSMOS field. It utilizes deep narrow-band (NB) imaging to photometrically detect faint Ly α forest transmission in background galaxies across the Subaru/Hyper-Suprime Cam (HSC)’s $1.8\rm \, sq.\, deg$ field of view and locate Ly α emitters (LAEs) in the same cosmic volume. Using ultra-deep HSC images and Bayesian spectral energy distribution fitting, we measure the Ly α forest transmission at z ≃ 4.9 along a large number (140) of background galaxies selected from the DEIMOS10k spectroscopic catalogue at 4.98 < z < 5.89 and the SILVERRUSH LAEs at z ≃ 5.7. We photometrically measure the mean Ly α forest transmission and achieve a result consistent with previous measurements based on quasar spectra. We also measure the angular LAE-Ly α forest cross-correlation and Ly α forest autocorrelation functions and place an observational constraint on the large-scale fluctuations of the IGM around LAEs at z ≃ 4.9. Finally, we present the reconstructed 2D tomographic map of the IGM, co-spatial with the large-scale structure of LAEs, at a transverse resolution of $11 \, h^{-1}\rm cMpc$ across $140\, h^{-1}\rm cMpc$ in the COSMOS field at z ≃ 4.9. We discuss the observational requirements and the potential applications of this new technique for understanding the sources of reionization, quasar radiative history, and galaxy–IGM correlations across z ∼ 3–6. Our results represent the first proof-of-concept of photometric IGM tomography, offering a new route to examining early galaxy evolution in the context of the large-scale cosmic web from the epoch of reionization to cosmic noon.
PubDate: Mon, 08 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1376
Issue No: Vol. 523, No. 2 (2023)
- Growing evidence for high-energy neutrinos originating in radio blazars
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Pages: 1799 - 1808
Abstract: ABSTRACTEvidence for bright-radio blazars being high-energy neutrino sources was found in recent years. However, specifics of how and where these particles get produced still need to be determined. In this paper, we add 14 new IceCube events from 2020–2022 to update our analysis of the neutrino-blazars connection. We test and refine earlier findings by utilizing the total of 71 track-like high-energy IceCube events from 2009–2022. We correlate them with the complete sample of 3412 extragalactic radio sources selected by their compact radio emission. We demonstrate that neutrinos are statistically associated with radio-bright blazars with a post-trial p-value of 3 · 10−4. In addition to this statistical study, we confirm previous individual neutrino-blazar associations, find and discuss several new ones. Notably, PKS 1741 − 038 was selected earlier and had a second neutrino detected from its direction in 2022; PKS 0735 + 168 has experienced a major flare across the whole electromagnetic spectrum coincidently with a neutrino arrival from that direction in 2021.
PubDate: Tue, 16 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1467
Issue No: Vol. 523, No. 2 (2023)
- Sunspot positions from observations by Flaugergues in the Dalton Minimum
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Pages: 1809 - 1821
Abstract: ABSTRACTFrench astronomer Honoré Flaugergues compiled astronomical observations in a series of handwritten notebooks for 1782–1830, which are preserved at Paris Observatory. We reviewed these manuscripts and encoded the records that contain sunspot measurements into a numerical table for further analysis. All measurements are timings, and we found three types of measurements, allowing the reconstruction of heliographic coordinates. In the first case, the Sun and sunspots cross vertical and horizontal wires; in the second case, one vertical and two mirror-symmetric oblique wires; and in the third case, a rhombus-shaped set of wires. Additionally, timings of two solar eclipses also provided a few sunspot coordinates. As a result, we present the time–latitude (butterfly) diagram of the reconstructed sunspot coordinates, which covers the period of the Dalton Minimum and confirms consistency with those of Derfflinger and Prantner. We identify four solar cycles in this diagram and discuss the observed peculiarities as well as the data reliability.
PubDate: Tue, 16 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1489
Issue No: Vol. 523, No. 2 (2023)
- Equivalence between simple multilayered and homogeneous laboratory-based
rheological models in planetary science-
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Pages: 1822 - 1831
Abstract: ABSTRACTThe goal of this work is to investigate under which circumstances the tidal response of a stratified body can be approximated by that of a homogeneous body. We show that any multilayered planet model can be approximated by a homogeneous body, with the same dissipation of tidal energy as a function of the excitation frequency, as long as the rheology of the homogeneous model is sufficiently complex. Moreover we provide two straightforward methods for finding the parameters of the homogeneous rheology that would exhibit the same tidal response as the layered body. These results highlight the fact that the two models cannot be distinguished from each other only by the measurement of the second degree tidal Love number and quality factor, and that we do not need the complexity of the multilayer planet model in order to estimate its tidal dissipation. The methodology promises a great simplification of the treatment of multilayered bodies in numerical simulations because the treatment of a homogeneous body – even with a complex rheological model – can be computationally better handled than that of a multilayered planet.
PubDate: Wed, 17 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1496
Issue No: Vol. 523, No. 2 (2023)
- Identification of molecular clouds in emission maps: a comparison between
methods in the 13CO/C18O (J = 3–2) Heterodyne Inner Milky Way Plane
Survey-
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Pages: 1832 - 1852
Abstract: ABSTRACTThe growing range of automated algorithms for the identification of molecular clouds and clumps in large observational data sets has prompted the need for the direct comparison of these procedures. However, these methods are complex and testing for biases is often problematic: only a few of them have been applied to the same data set or calibrated against a common standard. We compare the Fellwalker method, a widely used watershed algorithm, to the more recent Spectral Clustering for Interstellar Molecular Emission Segmentation (SCIMES). SCIMES overcomes sensitivity and resolution biases that plague many friends-of-friends algorithms by recasting cloud segmentation as a clustering problem. Considering the 13CO/C18O (J = 3–2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) and the CO High-Resolution Survey (COHRS), we investigate how these two different approaches influence the final cloud decomposition. Although the two methods produce largely similar statistical results over the CHIMPS dataset, FW appears prone to oversegmentation, especially in crowded fields where gas envelopes around dense cores are identified as adjacent, distinct objects. FW catalogue also includes a number of fragmented clouds that appear as different objects in a line-of-sight projection. In addition, cross-correlating the physical properties of individual sources between catalogues is complicated by different definitions, numerical implementations, and design choices within each method, which make it very difficult to establish a one-to-one correspondence between the sources.
PubDate: Thu, 18 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1507
Issue No: Vol. 523, No. 2 (2023)
- Parallel and perpendicular alignments of velocity gradient and magnetic
field observed in the molecular clouds L1478 and L1482-
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Pages: 1853 - 1866
Abstract: ABSTRACTStar formation is a complex process that typically occurs in dense regions of molecular clouds mainly regulated by magnetic fields, magnetohydrodynamic (MHD) turbulence, and self-gravity. However, it remains a challenging endeavour to trace the magnetic field and determine regions of gravitational collapse, where the star is forming. Based on the anisotropic properties of MHD turbulence, a new technique termed velocity gradient technique (VGT) has been proposed to address these challenges. In this study, we apply the VGT to two regions of the giant California Molecular Cloud (CMC), namely, L1478 and L1482, and analyse the difference in their physical properties. We use the 12CO (J = 2–1), 13CO (J = 2–1), and C18O (J = 2–1) emission lines observed with the Heinrich Hertz Submillimeter Telescope. We compare VGT results calculated in the resolutions of 3.3 and 10 arcmin to Planck polarization at 353 GHz and 10 arcmin to determine areas of MHD turbulence dominance and self-gravity dominance. We show that the resolution difference can introduce misalignment between the two measurements. We find the VGT-measured magnetic fields globally agree with those from Planck in L1478, suggesting self-gravity’s effect is insignificant. The best agreement appears in VGT-12CO. As for L1482, the VGT measurements are statistically perpendicular to the Planck polarization indicating the dominance of self-gravity. This perpendicular alignment is more significant in VGT-13CO and VGT-C18O.
PubDate: Tue, 23 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1513
Issue No: Vol. 523, No. 2 (2023)
- Investigating kinematics and dynamics of three open clusters towards
Galactic anticentre-
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Pages: 1867 - 1884
Abstract: ABSTRACTWe present the intracluster kinematics and dynamics of three open clusters: NGC 1193, NGC 2355, and King 12 by incorporating kinematical and photometric data from Gaia DR3, as well as a ground-based telescope. After selecting cluster members based on proper motion data, clusters’ fundamental and structural parameters are investigated. We found the clusters at distances of 4.45, 1.97, and 3.34 kpc from the Sun in the direction of the Galactic anticentre. The luminosity function of the cluster NGC 1193 is flat, whereas it advances towards the fainter ends of the other two clusters. We observed a dip in the luminosity function of King 12. The mass function slopes for all three clusters differ from the solar neighbourhood reported by Salpeter, with NGC 1193 and NGC 2355 being flatter and King 12 having a higher value than the Salpeter value. The intra-cluster kinematics depict that stars in King 12 are moving outwards due to tidal forces from the Galactic disc, which we confirmed by plotting the cluster’s orbit in the Galaxy. Stars in NGC 2355 are moving with smaller relative velocities and have zero mean relative motion, which signifies that the cluster is neither contracting nor evaporating. The Galactic orbits of NGC 1193 suggest that it is orbiting farther from the Galactic disc, and so is less impacted by the Galactic tidal forces.
PubDate: Thu, 18 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1517
Issue No: Vol. 523, No. 2 (2023)
- Rotation curves and dynamical masses of MaNGA barred galaxies
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Pages: 1885 - 1907
Abstract: ABSTRACTIn this paper we analyse a sample of 46 barred galaxies of MaNGA. Our goal is to investigate the stellar kinematics of these galaxies and obtain their rotation curves. Additionally, we aim to derive the total stellar and dynamical masses, as well as the maximum rotation velocity, in order to examine their distributions and scaling relations. Using the Pipe3D dataproducts publicly available we obtained the rotation curves, which were fitted considering two components of an axisymmetric Miyamoto–Nagai gravitational potential. We found a wide range of the maximum rotation velocities (117–340 ${\rm km\, s^{-1}}$), with a mean value of 200 ${\rm km\, s^{-1}}$. In addition we found that the total stellar and dynamical masses are in the range of log(Mstar/M⊙) = 10.1−11.5, with a mean value of log(Mstar/M⊙) = 10.8, and log(Mdyn/M⊙) = 10.4−12.0, with a mean value of log(Mdyn/M⊙) = 11.1, respectively. We found a strong correlation between dynamical mass and maximum velocity, between maximum velocity and magnitude, and between stellar mass and maximum velocity. According to these results, barred galaxies exhibit similar behaviour to that of normal spiral galaxies with respect to these relations, as well as in terms of the distribution of their dynamical mass and maximum rotation velocity. However, we found that the distribution of stellar masses of barred galaxies is statistically different from other samples including non-barred galaxies. Finally, analysing the galaxies that show nuclear activity, we find no difference with the rotation curves of normal galaxies.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1531
Issue No: Vol. 523, No. 2 (2023)
- The role of soft photon injection and heating in 21 cm cosmology
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Pages: 1908 - 1918
Abstract: ABSTRACTThe ARCADE radio excess and EDGES measurement remain puzzling. A link between the two has been previously considered, however, in this work we highlight an important related effect that was not analysed in detail before. By performing cosmological thermalization calculations with soft photon injection using cosmotherm, we show that for the 21 cm signal generation, the interplay between enhanced radio spectral distortions and the associated heating can hide a significant radio excess before the reionization era. We illustrate this effect for a simple power-law soft photon source in decaying particle scenarios. Even if simplistic, the uncovered link between CMB spectral distortions and 21 cm cosmology should apply to a much broader range of scenarios. This could significantly affect the constraints derived from existing and future 21 cm observations on the evolution of the ambient radio background. In particular, scenarios that would be ruled out by existing data without heating could become viable solutions once the heating is accounted for in the modelling. Our calculations furthermore highlight the importance of global 21 cm observations reaching into the dark ages, where various scenarios can potentially be distinguished.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1540
Issue No: Vol. 523, No. 2 (2023)
- Redshift evolution of the dark matter haloes shapes
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Pages: 1919 - 1932
Abstract: ABSTRACTIn this work, we aim at investigating the morphology evolution of Milky Way mass-like dark matter haloes selected from the cielo and IllustrisTNG projects. The connection between halo shapes and their environment has been studied in previous works at z = 0 but their connection remains yet to be fully understood. We focus on the evolution across cosmic time of the halo shapes and the relation with the infalling material, using hydrodynamical simulations. Our findings show that haloes tend to be more triaxial at earlier times as a consequence of stronger accretion in the direction of the filaments. As the haloes evolve towards a dominant isotropic accretion mode and relaxation, their shape at 20 per cent of the virial radius becomes more spherical. In agreement with previous results, baryons have an important effect within the inner regions of the haloes, driving them from triaxial to rounder shapes. We also find a correlation between the strength of the quadrupole infalling mode and the degree of ellipticity of the haloes: as the filament strength decreases steadily with redshift, the haloes became more spherical and less elliptical.
PubDate: Fri, 26 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1601
Issue No: Vol. 523, No. 2 (2023)
- MeerKAT view of the dancing ghosts – peculiar galaxy pair PKS
2130−538 in Abell 3785-
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Pages: 1933 - 1945
Abstract: ABSTRACTWe present MeerKAT L-band (886–1682 MHz) observations of the extended radio structure of the peculiar galaxy pair PKS 2130−538 known as the ‘Dancing Ghosts’. The complex of bending and possibly interacting jets and lobes originate from two active galactic nuclei hosts in the Abell 3785 galaxy cluster, one of which is the brightest cluster galaxy. The radio properties of the PKS 2130−538 – flux density, spectral index, and polarization – are typical for large, bent-tail galaxies. We also investigate a number of thin extended low surface brightness filaments originating from the lobes. South-east from the Dancing Ghosts, we detect a region of low surface brightness emission that has no clear origin. While it could originate from the Abell 3785 radio halo, we investigate the possibility that it is associated with the two PKS 2130−538 hosts. We find no evidence of interaction between the two PKS 2130−538 hosts.
PubDate: Tue, 02 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1307
Issue No: Vol. 523, No. 2 (2023)
- Mapping the X-ray variability of GRS 1915 + 105 with machine
learning-
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Pages: 1946 - 1966
Abstract: ABSTRACTBlack hole X-ray binary systems (BHBs) contain a close companion star accreting onto a stellar-mass black hole. A typical BHB undergoes transient outbursts during which it exhibits a sequence of long-lived spectral states, each of which is relatively stable. GRS 1915 + 105 is a unique BHB that exhibits an unequaled number and variety of distinct variability patterns in X-rays. Many of these patterns contain unusual behaviour not seen in other sources. These variability patterns have been sorted into different classes based on count rate and colour characteristics by previous work. In order to remove human decision-making from the pattern-recognition process, we employ an unsupervised machine learning algorithm called an auto-encoder to learn what classifications are naturally distinct by allowing the algorithm to cluster observations. We focus on observations taken by the Rossi X-ray Timing Explorer’s Proportional Counter Array. We find that the auto-encoder closely groups observations together that are classified as similar by previous work, but that there is reasonable grounds for defining each class as made up of components from three groups of distinct behaviour.
PubDate: Wed, 10 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1332
Issue No: Vol. 523, No. 2 (2023)
- SKA Science Data Challenge 2: analysis and results
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Pages: 1967 - 1993
Abstract: ABSTRACTThe Square Kilometre Array Observatory (SKAO) will explore the radio sky to new depths in order to conduct transformational science. SKAO data products made available to astronomers will be correspondingly large and complex, requiring the application of advanced analysis techniques to extract key science findings. To this end, SKAO is conducting a series of Science Data Challenges, each designed to familiarize the scientific community with SKAO data and to drive the development of new analysis techniques. We present the results from Science Data Challenge 2 (SDC2), which invited participants to find and characterize 233 245 neutral hydrogen (H i) sources in a simulated data product representing a 2000 h SKA-Mid spectral line observation from redshifts 0.25–0.5. Through the generous support of eight international supercomputing facilities, participants were able to undertake the Challenge using dedicated computational resources. Alongside the main challenge, ‘reproducibility awards’ were made in recognition of those pipelines which demonstrated Open Science best practice. The Challenge saw over 100 participants develop a range of new and existing techniques, with results that highlight the strengths of multidisciplinary and collaborative effort. The winning strategy – which combined predictions from two independent machine learning techniques to yield a 20 per cent improvement in overall performance – underscores one of the main Challenge outcomes: that of method complementarity. It is likely that the combination of methods in a so-called ensemble approach will be key to exploiting very large astronomical data sets.
PubDate: Wed, 31 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1375
Issue No: Vol. 523, No. 2 (2023)
- Modelling galaxy cluster triaxiality in stacked cluster weak lensing
analyses-
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Pages: 1994 - 2013
Abstract: ABSTRACTCounts of galaxy clusters offer a high-precision probe of cosmology, but control of systematic errors will determine the accuracy of this measurement. Using Buzzard simulations, we quantify one such systematic, the triaxiality distribution of clusters identified with the redMaPPer optical cluster finding algorithm, which was used in the Dark Energy Survey Year-1 (DES Y1) cluster cosmology analysis. We test whether redMaPPer selection biases the clusters’ shape and orientation and find that it only biases orientation, preferentially selecting clusters with their major axes oriented along the line of sight. Modelling the richness–mass relation as log-linear, we find that the log-richness amplitude ln (A) is boosted from the lowest to highest orientation bin with a significance of 14σ, while the orientation dependence of the richness-mass slope and intrinsic scatter is minimal. We also find that the weak lensing shear-profile ratios of cluster-associated dark haloes in different orientation bins resemble a ‘bottleneck’ shape that can be quantified with a Cauchy function. We test the correlation of orientation with two other leading systematics in cluster cosmology – miscentering and projection – and find a null correlation. The resulting mass bias predicted from our templates confirms the DES Y1 finding that triaxiality is a leading source of bias in cluster cosmology. However, the richness-dependence of the bias confirms that triaxiality does not fully resolve the tension at low-richness between DES Y1 cluster cosmology and other probes. Our model can be used for quantifying the impact of triaxiality bias on cosmological constraints for upcoming weak lensing surveys of galaxy clusters.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1404
Issue No: Vol. 523, No. 2 (2023)
- Effective two-body scatterings around a massive object
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Pages: 2014 - 2026
Abstract: ABSTRACTTwo-body scatterings under the potential of a massive object are very common in astrophysics. If the massive body is far enough away that the two small bodies are in their own gravitational sphere of influence, the gravity of the massive body can be temporarily ignored. However, this requires the scattering process to be fast enough that the small objects do not spend too much time at distances near the surface of the sphere of influence. In this paper, we derive the validation criteria for effective two-body scattering and establish a simple analytical solution for this process, which we verify through numerical scattering experiments. We use this solution to study star–black hole scatterings in the discs of active galactic nuclei and planet–planet scatterings in planetary systems, and calculate their one-dimensional cross-section analytically. Our solution will be valuable in reducing computational time when treating two-body scatterings under the potential of a much more massive third body, provided that the problem settings are in the valid parameter space region identified by our study.
PubDate: Tue, 16 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1442
Issue No: Vol. 523, No. 2 (2023)
- Partition function approach to non-Gaussian likelihoods: formalism and
expansions for weakly non-Gaussian cosmological inference-
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Pages: 2027 - 2038
Abstract: ABSTRACTNon-Gaussian likelihoods, ubiquitous throughout cosmology, are a direct consequence of non-linearities in the physical model. Their treatment requires Monte Carlo Markov chain (MCMC) or more advanced sampling methods for the determination of confidence contours. As an alternative, we construct canonical partition functions as Laplace transforms of the Bayesian evidence, from which MCMC methods would sample microstates. Cumulants of order n of the posterior distribution follow by direct n-fold differentiation of the logarithmic partition function, recovering the classic Fisher-matrix formalism at second order. We connect this approach for weakly non-Gaussianities to the DALI and Gram−Charlier expansions and demonstrate the validity with a supernova-likelihood on the cosmological parameters Ωm and w. We comment on extensions of the canonical partition function to include kinetic energies in order to bridge to Hamilton Monte Carlo sampling, and on ensemble Markov-chain methods, as they would result from transitioning to macrocanonical partition functions depending on a chemical potential. Lastly we demonstrate the relationship of the partition function approach to the Cramér−Rao boundary and to information entropies.
PubDate: Tue, 16 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1471
Issue No: Vol. 523, No. 2 (2023)
- Meridional circulation driven by planetary spiral wakes in radiative and
magnetized protoplanetary discs-
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Pages: 2039 - 2058
Abstract: ABSTRACTWe study a Jupiter-mass planet formation for the first time in radiative magnetohydrodynamics (MHD) simulations and compare it with pure hydrodynamical simulations, and also with different isothermal configurations. We found that the meridional circulation is the same in every set-up. The planetary spiral wakes drive a vertical stirring inside the protoplanetary disc and the encounter with these shock fronts also helps in delivering gas vertically on to the Hill sphere. The accretion dynamics are unchanged: the planet accretes vertically, and there is outflow in the mid-plane regions inside the Hill sphere. We determined the effective α-viscosity generated in the disc by the various angular momentum loss mechanisms, which showed that magnetic fields produce high turbulence in the ideal MHD limit, and grows from α ∼ 10−2.5 up to ∼10−1.5 after the planet spirals develop. In the HD simulations, the planetary spirals contribute to α ∼ 10−3, making this a very important angular momentum transport mechanism. Due to the various α values in the different set-ups, the gap opening is different in each case. In the radiative MHD set-ups, the high turbulent viscosity prevents gap opening, leading to a higher Hill mass, and no clear dust trapping regions. While the Hill accretion rate is $10^{-6}~ \rm {M_{Jup}\,yr^{-1}}$ in all set-ups, the accretion variability is orders of magnitude higher in radiative runs than in isothermal ones. Finally, with higher resolution runs, the magnetorotational instability started to be resolved, changing the effective viscosity and increasing the heating in the disc.
PubDate: Thu, 18 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1477
Issue No: Vol. 523, No. 2 (2023)
- Spatial eigenvalue problems for stars in hydrostatic equilibrium:
Generalized Lane–Emden equations as boundary value problems-
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Pages: 2059 - 2073
Abstract: ABSTRACTWe derive a generic spatial eigenvalue problem governing stars in hydrostatic equilibrium. Our approach generalizes the various Lane–Emden equations finding use over the past century, allowing for more general equations of state (EoS) while ensuring a stellar structure with finite size (without the need for artificial truncation of the radius). We show that the resulting stellar structure is encoded into two quantities: the eigenvalue, which determines the total size or mass of the star, and the density distribution, which encodes the internal structure. While our formalism recovers known results for polytrope and white dwarf EoS, we also study additional EoS, such as those incorporating excluded volumes or those calibrated through viral expansions. We obtain numerical values for the stellar structure under a variety of frameworks, comparing and contrasting stellar structure under different EoS. Interestingly, we show how different EoS can be calibrated to give solutions with the same stellar structure, highlighting the arbitrariness of a particular EoS for replicating observations. This leads us to comment on general properties EoS should obey to describe physically realistic stars. We also consider hydrostatic gas clouds immersed in larger regions having non-zero ambient density. We compare three analytical methods for finding solutions of these eigenvalue problems, including Taylor series solutions, the variational approximation, and the non-perturbative delta-expansion method. Although each method has benefits and drawbacks, we show that the delta-expansion method provides the most accuracy in replicating stellar structure.
PubDate: Wed, 17 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1506
Issue No: Vol. 523, No. 2 (2023)
- The effect of flow on transverse oscillations of two parallel magnetic
tubes-
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Pages: 2074 - 2082
Abstract: ABSTRACTWe study oscillations of two parallel interacting magnetic tubes in the presence of plasma flow along the tubes. Using the cold plasma and thin tube approximations we derive the system of two equations describing these oscillations. This system of equations is valid for equilibria where the plasma density and flow velocity can vary along the tube axes and in time. This system of equations is used to study the effect of flow in the tubes on the frequency of standing waves. There are two modes of oscillations, fast and slow. We calculated the dependence of frequencies of fast and slow modes of the Alfvén Mach number. We found that the effect of flow in coronal loops on the oscillation frequency is fairly weak for typical flow velocities observed in coronal loops. However it can be substantial in the case of prominence threads. We discuss the implication of the obtained results on coronal seismology.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1530
Issue No: Vol. 523, No. 2 (2023)
- Star cluster formation from turbulent clumps – III. Across the mass
spectrum-
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Pages: 2083 - 2110
Abstract: ABSTRACTWe study the formation and early evolution of star clusters that have a wide range of masses and background cloud mass surface densities, Σcloud, which help set the initial sizes, densities, and velocity dispersions of the natal gas clumps. Initial clump masses of 300, 3000, and 30 000 M⊙ are considered, from which star clusters are born with an assumed 50 per cent overall star formation efficiency and with 50 per cent primordial binarity. This formation is gradual, i.e. with a range of star formation efficiencies per free-fall time from 1 to 100 per cent, so that the formation time can range from 0.7 Myr for low-mass, high-Σcloud clumps to ∼30 Myr for high-mass, low-Σcloud clumps. Within this framework of the turbulent clump model, for a given Σcloud, clumps of higher mass are of lower initial volume density, but their dynamical evolution leads to higher bound fractions and causes them to form much higher density cluster cores and maintain these densities for longer periods. This results in systematic differences in the evolution of binary properties, degrees of mass segregation, and rates of creation of dynamically ejected runaways. We discuss the implications of these results for observed star clusters and stellar populations.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1532
Issue No: Vol. 523, No. 2 (2023)
- The Pristine Inner Galaxy Survey (PIGS) VII: a discovery of the first
inner Galaxy CEMP-r/s star-
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Pages: 2111 - 2125
Abstract: ABSTRACTWell-studied very metal-poor (VMP, [Fe/H] <−2) stars in the inner Galaxy are few in number, and they are of special interest because they are expected to be among the oldest stars in the Milky Way. We present high-resolution spectroscopic follow-up of the carbon-enhanced metal-poor (CEMP) star Pristine_184237.56-260624.5 (hereafter Pr184237) identified in the Pristine Inner Galaxy Survey. This star has an apocentre of ∼2.6 kpc. Its atmospheric parameters (Teff = 5100 K, log g = 2.0, and [Fe/H] = −2.60) were derived based on the non-local thermodynamic equilibrium (NLTE) line formation. We determined abundances for 32 elements, including 15 heavy elements beyond the iron group. The NLTE abundances were calculated for 13 elements from Na to Pb. Pr184237 is strongly enhanced in C, N, and O, and both s- and r-process elements from Ba to Pb; it reveals a low carbon isotope ratio of 12C/13C = 7. The element abundance pattern in the Na–Zn range is typical of halo stars. With [Ba/Eu] = 0.32, Pr184237 is the first star of the CEMP-r/s subclass identified in the inner Galaxy. Variations in radial velocity suggest binarity. We tested whether a pollution by the s- or i-process material produced in the more massive and evolved companion can form the observed abundance pattern and find that an i-process in the asymptotic giant branch star with a progenitor mass of 1.0–2.0 $\, {\rm M}_{\odot }$ can be the solution.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1536
Issue No: Vol. 523, No. 2 (2023)
- On the origin of the Galactic thin and thick discs, their abundance
gradients and the diagnostic potential of their abundance ratios-
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Pages: 2126 - 2145
Abstract: ABSTRACTUsing a semi-analytical model of the evolution of the Milky Way, we show how secular evolution can create distinct overdensities in the phase space of various properties (e.g. age versus metallicity or abundance ratios versus age) corresponding to the thin and thick discs. In particular, we show how key properties of the Solar vicinity can be obtained by secular evolution, with no need for external or special events, like galaxy mergers or paucity in star formation. This concerns the long established double-branch behaviour of [alpha/Fe] versus metallicity and the recently found non-monotonic evolution of the stellar abundance gradient, evaluated at the birth radii of stars. We extend the discussion to other abundance ratios and we suggest a classification scheme, based on the nature of the corresponding yields (primary versus secondary or odd elements) and on the lifetimes of their sources (short-lived versus long-lived ones). The latter property is critical in determining the single- or double- branch behaviour of an elementary abundance ratio in the Solar neighbourhood. We underline the high diagnostic potential of this finding, which can help to separate clearly elements with sources evolving on different time-scales and help determining the site of e.g. the r-process(es). We define the ‘abundance distance’ between the thin and thick disc sequences as an important element for such a separation. We also show how the inside-out evolution of the Milky Way disc leads rather to a single-branch behaviour in other disc regions.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1551
Issue No: Vol. 523, No. 2 (2023)
- Influence of Gaunt factors on the calculation of the Stark broadening
parameters for 56 spectral lines of V ii with high industrial and
astrophysical interest-
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Pages: 2146 - 2157
Abstract: ABSTRACTRecently, in 2020, Stark broadening parameters have been measured for spectral lines belonging to 75 vanadium ii (V ii) multiplets. For some of them, there are published calculations in the literature. However, these lines are not sufficient for the analysis of the lines present in the metal-poor star HD 8493. When new calculations by the Griem approximation are performed and compared with the experimental results, in some cases there is a difference of a factor of 7. It is clear that the problem lies, as already suggested some years ago in a theoretical paper by Douglas H. Sampson, in the poor approximation proposed by van Regemorter for the Gaunt factors used in the Griem approximation. In this work, we have performed broadening measurements of 3276.12 and 3715.46 Å V ii lines that confirmed the previous measurements of 2020. Subsequently, we performed a more accurate calculation using the procedure to calculate the Gaunt factors suggested by Sampson, obtaining results very close to the experimental values. These allowed us to assume that the calculations performed for 56 lines ranging between 3700 and 4600 Å (present in the photospheres of the Sun and the metal-poor star HD 8493), and without experimental information, are more accurate using the Gaunt factors proposed by Sampson.
PubDate: Tue, 23 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1555
Issue No: Vol. 523, No. 2 (2023)
- Constraints on the ultrafast outflows in the narrow-line Seyfert 1 galaxy
Mrk 1044 from high-resolution time- and flux-resolved spectroscopy-
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Pages: 2158 - 2171
Abstract: ABSTRACTUltrafast outflows (UFOs) have been revealed in a large number of active galactic nuclei (AGN) and are regarded as promising candidates for AGN feedback on the host galaxy. The nature and launching mechanism of UFOs are not yet fully understood. Here we perform a time- and flux-resolved X-ray spectroscopy on four XMM–Newton observations of a highly accreting narrow-line Seyfert 1 (NLS1) galaxy, Mrk 1044, to study the dependence of the outflow properties on the source luminosity. We find that the UFO in Mrk 1044 responds to the source variability quickly and its velocity increases with the X-ray flux, suggesting a high-density ($10^{9}\!-\!4.5\times 10^{12}\, \mathrm{cm}^{-3}$) and radiatively driven outflow, launched from the region within a distance of $98\!-\!6600\, R_\mathrm{g}$ from the black hole. The kinetic energy of the UFO is conservatively estimated ($L_\mathrm{UFO}\sim 4.4~{{\ \rm per\ cent}}\, L_\mathrm{Edd}$), reaching the theoretical criterion to affect the evolution of the host galaxy. We also find that emission lines, from a large-scale region, have a blueshift of 2700–4500 km s−1 in the spectra of Mrk 1044, which is rarely observed in AGN. By comparing with other sources, we propose a correlation between the blueshift of emission lines and the source accretion rate, which can be verified by a future sample study.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1565
Issue No: Vol. 523, No. 2 (2023)
- Minute-cadence observations of the LAMOST fields with the TMTS: II.
Catalogues of short-period variable stars from the first 2-yr surveys-
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Pages: 2172 - 2192
Abstract: ABSTRACTOver the past few years, wide-field time-domain surveys such as Zwicky Transient Facility and Optical Gravitational Lensing Experiment have led to discoveries of various types of interesting short-period stellar variables, such as ultracompact eclipsing binary white dwarfs (WDs), rapidly rotating magnetized WDs, transitional cataclysmic variables between hydrogen-rich and helium accretion, and blue large-amplitude pulsators (BLAPs), which greatly enrich our understandings of stellar physics under some extreme conditions. In this paper, we report the first-2-yr discoveries of short-period variables (i.e. P < 2 h) by the Tsinghua University–Ma Huateng Telescopes for Survey (TMTS). TMTS is a multitube telescope system with a field of view up to 18 deg2, which started to monitor the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST) sky areas since 2020 and generated uninterrupted minute-cadence light curves for about 10 million sources within 2 yr. Adopting the Lomb–Scargle periodogram with period-dependent thresholds for the maximum powers, we identify over 1100 sources that exhibit a variation period shorter than 2 h. Compiling the light curves with the Gaia magnitudes and colours, LAMOST spectral parameters, International Variable Star Index classifications, and archived observations from other prevailing time-domain survey missions, we identified 1076 as δ Scuti stars, which allows us to study their populations and physical properties in the short-period regime. The other 31 sources include BLAPs, subdwarf B variables, pulsating WDs, ultracompact/short-period eclipsing/ellipsoidal binaries, cataclysmic variables below the period gap, etc., which are highly interesting and worthy of follow-up investigations.
PubDate: Thu, 01 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad994
Issue No: Vol. 523, No. 2 (2023)
- Minute-cadence observations of the LAMOST fields with the TMTS – III.
Statistical study of the flare stars from the first two years-
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Pages: 2193 - 2208
Abstract: ABSTRACTTsinghua University-Ma Huateng Telescopes for Survey (TMTS) aims to detect fast-evolving transients in the Universe, which has led to the discovery of thousands of short-period variables and eclipsing binaries since 2020. In this paper, we present the observed properties of 125 flare stars identified by TMTS within the first two years, with an attempt to constrain their eruption physics. As expected, most of these flares were recorded in late-type red stars with GBP − GRP >2.0 mag; however, the flares associated with bluer stars tend to be on average more energetic and have broader profiles. The peak flux (Fpeak) of the flare is found to depend strongly on the equivalent duration (ED) of the energy release, i.e. Fpeak∝ED0.72 ± 0.04, which is consistent with results derived from the Kepler and Evryscope samples. This relation is likely to be related to the magnetic loop emission, while, for the more popular non-thermal electron heating model, a specific time evolution may be required to generate this relation. We notice that flares produced by hotter stars have a flatter Fpeak - ED relation compared to that from cooler stars. This is related to the statistical discrepancy in light-curve shape of flare events with different colours. In spectra from LAMOST, we find that flare stars have apparently stronger H α emission than inactive stars, especially at the low-temperature end, suggesting that chromospheric activity plays an important role in producing flares. On the other hand, the subclass with frequent flares is found to show H α emission of similar strength in its spectra to that recorded with only a single flare but similar effective temperature, implying that chromospheric activity may not be the only trigger for eruptions.
PubDate: Thu, 01 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad365
Issue No: Vol. 523, No. 2 (2023)
- On the growth of supermassive black holes formed from the gravitational
collapse of fermionic dark matter cores-
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Pages: 2209 - 2218
Abstract: ABSTRACTObservations support the idea that supermassive black holes (SMBHs) power the emission at the centre of active galaxies. However, contrary to stellar-mass BHs, there is a poor understanding of their origin and physical formation channel. In this article, we propose a new process of SMBH formation in the early Universe that is not associated with baryonic matter (massive stars) or primordial cosmology. In this novel approach, SMBH seeds originate from the gravitational collapse of fermionic dense dark matter (DM) cores that arise at the centre of DM haloes as they form. We show that such a DM formation channel can occur before star formation, leading to heavier BH seeds than standard baryonic channels. The SMBH seeds subsequently grow by accretion. We compute the evolution of the mass and angular momentum of the BH using a geodesic general relativistic disc accretion model. We show that these SMBH seeds grow to ∼109–$10^{10} \, \mathrm{M}_\odot$ in the first Gyr of the lifetime of the Universe without invoking unrealistic (or fine-tuned) accretion rates.
PubDate: Wed, 31 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1380
Issue No: Vol. 523, No. 2 (2023)
- Bursts from Space: MeerKAT – the first citizen science project dedicated
to commensal radio transients-
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Pages: 2219 - 2235
Abstract: ABSTRACTThe newest generation of radio telescopes is able to survey large areas with high sensitivity and cadence, producing data volumes that require new methods to better understand the transient sky. Here, we describe the results from the first citizen science project dedicated to commensal radio transients, using data from the MeerKAT telescope with weekly cadence. Bursts from Space: MeerKAT was launched late in 2021 and received ∼89 000 classifications from over 1000 volunteers in 3 months. Our volunteers discovered 142 new variable sources which, along with the known transients in our fields, allowed us to estimate that at least 2.1 per cent of radio sources are varying at 1.28 GHz at the sampled cadence and sensitivity, in line with previous work. We provide the full catalogue of these sources, the largest of candidate radio variables to date. Transient sources found with archival counterparts include a pulsar (B1845-01) and an OH maser star (OH 30.1–0.7), in addition to the recovery of known stellar flares and X-ray binary jets in our observations. Data from the MeerLICHT optical telescope, along with estimates of long time-scale variability induced by scintillation, imply that the majority of the new variables are active galactic nuclei. This tells us that citizen scientists can discover phenomena varying on time-scales from weeks to several years. The success both in terms of volunteer engagement and scientific merit warrants the continued development of the project, while we use the classifications from volunteers to develop machine learning techniques for finding transients.
PubDate: Thu, 11 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1298
Issue No: Vol. 523, No. 2 (2023)
- Three approaches for the classification of protoneutron star oscillation
modes-
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Pages: 2236 - 2246
Abstract: ABSTRACTThe future detection of gravitational waves (GWs) from a Galactic core-collapse supernova will provide information on the physics inside protoneutron stars (PNS). In this work, we apply three different classification methods for the PNS non-radial oscillation modes: Cowling classification, Generalized Cowling Nomenclature (GCN), and a classification based on modal properties (CBMP). Using PNS models from 3D simulations of core-collapse supernovae, we find that in the early stages of the PNS evolution, typically 0.4 s after the bounce, the Cowling classification is inconsistent, but the GCN and the CBMP provide complementary information that helps to understand the evolution of the modes. In the GCN, we note several avoided crossings as the mode frequencies evolve at early times, while the CBMP tracks the modes across the avoided crossings. We verify that the strongest emission of GWs by the PNS corresponds to the f mode in the GCN, indicating that the mode trapping region alternates between the core and the envelope at each avoided crossing. At later times, approximately 0.4 s after the bounce, the three classification methods present a similar description of the mode spectrum. We use our results to test universal relations for the PNS modes according to their classification and find that the behaviour of the universal relations for f and p modes is remarkably simple in the CBMP.
PubDate: Mon, 15 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1459
Issue No: Vol. 523, No. 2 (2023)
- SP(k) – a hydrodynamical simulation-based model for the impact of baryon
physics on the non-linear matter power spectrum-
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Pages: 2247 - 2262
Abstract: ABSTRACTUpcoming large-scale structure surveys will measure the matter power spectrum to approximately per cent level accuracy with the aim of searching for evidence for new physics beyond the standard model of cosmology. In order to avoid biasing our conclusions, the theoretical predictions need to be at least as accurate as the measurements for a given choice of cosmological parameters. However, recent theoretical work has shown that complex physical processes associated with galaxy formation (particularly energetic feedback processes associated with stars and especially supermassive black holes) can alter the predictions by many times larger than the required accuracy. Here we present SP(k), a model for the effects of baryon physics on the non-linear matter power spectrum based on a new large suite of hydrodynamical simulations. Specifically, the ANTILLES suite consists of 400 simulations spanning a very wide range of the ‘feedback landscape’ and show that the effects of baryons on the matter power spectrum can be understood at approaching the per cent level in terms of the mean baryon fraction of haloes, at scales of up to $k \, {\lesssim } \, 10\, h$ Mpc−1 and redshifts up to z = 3. For the range of scales and redshifts that will be probed by forthcoming cosmic shear measurements, most of the effects are driven by galaxy group mass haloes (M ∼ 1013–14 M⊙). We present a simple python implementation of our model, available at https://github.com/jemme07/pyspk, which can be used to incorporate baryon effects in standard gravity-only predictions, allowing for marginalization over baryon physics within cosmological pipelines.
PubDate: Tue, 16 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1474
Issue No: Vol. 523, No. 2 (2023)
- Studying the warm hot intergalactic medium in emission: a reprise
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Pages: 2263 - 2282
Abstract: ABSTRACTThe warm-hot intergalactic medium (WHIM) contains a significant portion of the ‘missing baryons’. Its detection in emission remains a challenge. Integral field spectrometers like X-IFU on board of the Athena satellite will secure WHIM detection in absorption and emission and, for the first time, allow us to investigate its physical properties. In our research, we use the CAMELS simulations to model the surface brightness maps of the OVII and OVIII ion lines and compute summary statistics like photon counts and 2-point correlation functions to infer the properties of the WHIM. Our findings confirm that detectable WHIM emission is primarily associated with galaxy haloes, and the properties of the WHIM show minimal evolution from z ∼ 0.5 to the present time. By exploring a wide range of parameters within the CAMELS suite, we investigate the sensitivity of WHIM properties to cosmology and energy feedback mechanisms influenced by active galactic nuclei and stellar activity. This approach allows us to separate the cosmological aspects from the baryonic processes and place constraints on the latter. Additionally, we provide forecasts for WHIM observations using a spectrometer similar to X-IFU. We anticipate detecting 1–3 WHIM emission lines per pixel and mapping the WHIM emission profile around haloes up to a few tens of arcminutes, surpassing the typical size of a WHIM emitter. Overall, our work demonstrates the potential of emission studies to probe the densest phase of the WHIM, shedding light on its physical properties and offering insights into the cosmological and baryonic processes at play.
PubDate: Thu, 18 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1495
Issue No: Vol. 523, No. 2 (2023)
- A geometric calibration of the tip of the red giant branch in the Milky
Way using Gaia DR3-
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Pages: 2283 - 2295
Abstract: ABSTRACTWe use the latest parallaxes measurements from Gaia DR3 to obtain a geometric calibration of the tip of the red giant branch (TRGB) in Cousins I magnitudes as a standard candle for cosmology. We utilize the following surveys: SkyMapper DR3, APASS DR9, ATLAS Refcat2, and Gaia DR3 synthetic photometry to obtain multiple zero-point calibrations of the TRGB magnitude, $M_{I}^{TRGB}$. Our sample contains Milky Way halo stars at high galactic latitudes ( b > 36) where the impact of metallicity, dust, and crowding are minimized. The magnitude of the TRGB is identified using Sobel edge detection, but this approach introduced a systematic offset. To address this issue, we utilized simulations with parsec isochrones and showed how to calibrate and remove this bias. Applying our method within the colour range where the slope of the TRGB is relatively flat for metal-poor halo stars (1.55 < (BP − RP) < 2.25), we find a weighted average $M_{I}^{TRGB} = -4.042 \pm 0.041$ (stat) ±0.031 (sys) mag. A geometric calibration of the Milky Way TRGB has the benefit of being independent of other distance indicators and will help probe systematics in the local distance ladder, leading to improved measurements of the Hubble constant.
PubDate: Wed, 17 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1500
Issue No: Vol. 523, No. 2 (2023)
- Role of ionizing background on the statistics of metal absorbers in
hydrodynamical simulations-
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Pages: 2296 - 2316
Abstract: ABSTRACTWe study the statistical properties of O vi, C iv, and Ne viii absorbers at low-z (i.e. z < 0.5) using Sherwood simulations with ‘WIND’ only and ‘WIND + AGN’ feedback and massive black-II simulation that incorporates both ‘WIND’ i.e. outflows driven by stellar feedback and active galactic nucleus (AGN) feedbacks. For each simulation, by considering a wide range of metagalactic ionizing ultraviolet background (UVB), we show the statistical properties such as distribution functions of column density (N), b-parameter and velocity spread (ΔV90), the relationship between N and b-parameter, and the fraction of Ly α absorbers showing detectable metal lines as a function of N(H i) are influenced by the UVB used. This is because UVB changes the range in density, temperature, and metallicity of gas contributing to a given absorption line. For simulations considered here, we show the difference in some of the predicted distributions between different simulations is similar to the one obtained by varying the UVB for a given simulation. Most of the observed properties of O vi absorbers are roughly matched by Sherwood simulation with ‘WIND + AGN’ feedback when using the UVB with a lower O vi ionization rate. However, this simulation fails to produce observed distributions of C iv and fraction of H i absorbers with detectable metals. Therefore, in order to constrain different feedback processes and/or UVBs, using observed properties of H i and metal ions, it is important to perform simultaneous analysis of various observable parameters.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1550
Issue No: Vol. 523, No. 2 (2023)
- 3D stellar evolution: hydrodynamic simulations of a complete burning phase
in a massive star-
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Pages: 2317 - 2328
Abstract: ABSTRACTOur knowledge of stellar evolution is driven by one-dimensional (1D) simulations. 1D models, however, are severely limited by uncertainties on the exact behaviour of many multidimensional phenomena occurring inside stars, affecting their structure and evolution. Recent advances in computing resources have allowed small sections of a star to be reproduced with multi-D hydrodynamic models, with an unprecedented degree of detail and realism. In this work, we present a set of 3D simulations of a convective neon-burning shell in a 20 M⊙ star run for the first time continuously from its early development through to complete fuel exhaustion, using unaltered input conditions from a 321D-guided 1D stellar model. These simulations help answer some open questions in stellar physics. In particular, they show that convective regions do not grow indefinitely due to entrainment of fresh material, but fuel consumption prevails over entrainment, so when fuel is exhausted convection also starts decaying. Our results show convergence between the multi-D simulations and the new 321D-guided 1D model, concerning the amount of convective boundary mixing to include in stellar models. The size of the convective zones in a star strongly affects its structure and evolution; thus, revising their modelling in 1D will have important implications for the life and fate of stars. This will thus affect theoretical predictions related to nucleosynthesis, supernova explosions, and compact remnants.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1572
Issue No: Vol. 523, No. 2 (2023)
- A search for the missing baryons with X-ray absorption lines towards the
blazar 1ES 1553+113-
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Pages: 2329 - 2350
Abstract: ABSTRACTThis paper presents an analysis of XMM–Newton and Chandra X-ray spectra of the quasar 1ES 1553+113, in search for absorption lines from the intervening warm–hot intergalactic medium (WHIM). A search for O vii, O viii, and Ne ix resonance absorption lines was performed at eight fixed redshifts that feature O vi or H i broad Lyman α absorption lines that were previously detected from Hubble Space Telescope (HST) data. The search yielded one possible detection of O vii at a redshift z ≃ 0.1877 with an O vi prior, with a statistical significance that is equivalent to a 2.6σ confidence level. The spectra were also stacked at the wavelengths of the expected redshifted O vii and O viii lines, but the analysis did not reveal evidence for the presence of additional X-ray absorbing WHIM. Moreover, the spectra were used to investigate two putative O vii absorption lines that were detected serendipitously in an earlier analysis of the same data by F. Nicastro and collaborators. The paper also presents a comprehensive statistical framework for cosmological inferences from the analysis of absorption lines, which makes use of cosmological simulations for the joint probability distributions of far-ultraviolet (FUV) and X-ray ions. Accordingly, we conclude that the new possible O vii absorption at z ≃ 0.1877 is consistent with a contribution from the hot WHIM to the baryon density in an amount of ΩWHIM, X/Ωb = 44 ± 22 per cent. However, there are large systematic uncertainties associated with the temperature and abundances of the absorbers, and only a larger sample of X-ray sources can provide an accurate determination of the cosmological density of the WHIM.
PubDate: Mon, 05 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1345
Issue No: Vol. 523, No. 2 (2023)
- A Bayesian chemical evolution model of the DustPedia galaxy M74
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Pages: 2351 - 2368
Abstract: ABSTRACTWe introduce a new, multizone chemical evolution model of the DustPedia galaxy M74, calibrated by means of Markov Chain Monte Carlo methods. We take into account the observed stellar and gas density profiles and use Bayesian analysis to constrain two fundamental parameters characterizing the gas accretion and star formation time-scale, i.e. the infall time-scale τ and the SF efficiency ν, respectively, as a function of galactocentric radius R. Our analysis supports an infall time-scale increasing with R and a star formation efficiency decreasing with R, thus supporting an ‘Inside-Out’ formation for M74. For both τ and ν, we find a weaker radial dependence than in the Milky Way. We also investigate the dust content of M74, comparing the observed dust density profile with the results of our chemical evolution models. Various prescriptions have been considered for two key parameters, i.e. the typical dust accretion time-scale τ0 and the mass of gas cleared out of dust by a supernova remnant, Mclear, regulating the dust growth and destruction rate, respectively. Two models with a different current balance between destruction and accretion, i.e. with an equilibrium and a dominion of accretion over destruction, can equally reproduce the observed dust profile of M74. This outlines the degeneracy between these parameters in shaping the interstellar dust content in galaxies. Our methods will be extended to more DustPedia galaxies to shed more light on the relative roles of dust production and destruction.
PubDate: Mon, 08 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1316
Issue No: Vol. 523, No. 2 (2023)
- The period–luminosity relation for Mira variables in the Milky Way using
Gaia DR3: a further distance anchor for H0-
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Pages: 2369 - 2398
Abstract: ABSTRACTGaia DR3 parallaxes are used to calibrate preliminary period–luminosity relations of O-rich Mira variables in the 2MASS J, H, and Ks bands using a probabilistic model accounting for variations in the parallax zero-point and underestimation of the parallax uncertainties. The derived relations are compared to those measured for the Large and Small Magellanic Clouds, the Sagittarius dwarf spheroidal galaxy, globular cluster members, and the subset of Milky Way Mira variables with VLBI parallaxes. The Milky Way linear JHKs relations are slightly steeper and thus fainter at short period than the corresponding LMC relations, suggesting population effects in the near-infrared are perhaps larger than previous observational works have claimed. Models of the Gaia astrometry for the Mira variables suggest that, despite the intrinsic photocentre wobble and use of mean photometry in the astrometric solution of the current data reduction, the recovered parallaxes should be on average unbiased but with underestimated uncertainties for the nearest stars. The recommended Gaia EDR3 parallax zero-point corrections evaluated at $\nu _\mathrm{eff}=1.25\, \mu \mathrm{m}^{-1}$ require minimal ($\lesssim 5\, \mu \mathrm{as}$) corrections for redder five-parameter sources, but overcorrect the parallaxes for redder six-parameter sources, and the parallax uncertainties are underestimated at most by a factor ∼1.6 at $G\approx 12.5\, \mathrm{mag}$. The derived period–luminosity relations are used as anchors for the Mira variables in the Type Ia host galaxy NGC 1559 to find $H_0=(73.7\pm 4.4)\, \mathrm{km\, s}^{-1}\, \mathrm{Mpc}^{-1}$.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1431
Issue No: Vol. 523, No. 2 (2023)
- Correction to: Kinetic theory and fast wind observations of the electron
strahl-
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Pages: 2399 - 2400
Abstract: errata, addendaplasmasscatteringsolar wind
PubDate: Mon, 05 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1443
Issue No: Vol. 523, No. 2 (2023)
- Simultaneous radio and X-ray observations of the magnetar Swift
J1818.0−1607-
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Pages: 2401 - 2408
Abstract: ABSTRACTSwift J1818.0−1607 is a radio-emitting magnetar that was discovered in X-ray outburst in 2020 March. Starting 4 d after this outburst, we began a nearly 5-month multifrequency observing campaign at 2.2, 8.4, and 32 GHz using telescopes in the NASA Deep Space Network. Using a dual-frequency observing mode, we were able to observe Swift J1818.0−1607 simultaneously at either 2.2 and 8.4 GHz or 8.4 and 32 GHz. Over the course of the campaign, we find that the flux density increases substantially and the spectrum changes from uncharacteristically steep (α < −2.2) to the essentially flat (α ≈ 0) spectrum typical of radio-emitting magnetars. In addition to the expected profile evolution on time-scales of days to months, we find that Swift J1818.0−1607 also exhibits mode switching where the pulse profile changes between two distinct shapes on time-scales of seconds to minutes. For two of the radio observations, we also had accompanying X-ray observations using the Neutron Star Interior Composition Explorer telescope that occurred on the same day. We find a near anti-alignment (0.40 phase cycles) between the peaks of the radio and X-ray pulse profiles, which is most likely explained by an intrinsic misalignment between the X-ray- and radio-emitting regions.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1520
Issue No: Vol. 523, No. 2 (2023)
- The impact of AGN-driven winds on physical and observable galaxy sizes
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Pages: 2409 - 2421
Abstract: ABSTRACTWithout active galactic nucleus (AGN) feedback, simulated massive, star-forming galaxies become too compact relative to observed galaxies at z ≲ 2. In this paper, we perform high-resolution re-simulations of a massive ($M_{\star }\sim 10^{11}\, \rm {{\rm M}_{\odot }}$) galaxy at z ∼ 2.3, drawn from the Feedback in Realistic Environments (FIRE) project. In the simulation without AGN feedback, the galaxy experiences a rapid starburst and shrinking of its half-mass radius. We experiment with driving mechanical AGN winds, using a state-of-the-art hyper-Lagrangian refinement technique to increase particle resolution. These winds reduce the gas surface density in the inner regions of the galaxy, suppressing the compact starburst and maintaining an approximately constant half-mass radius. Using radiative transfer, we study the impact of AGN feedback on the magnitude and extent of the multiwavelength continuum emission. When AGN winds are included, the suppression of the compact, dusty starburst results in lowered flux at FIR wavelengths (due to decreased star formation) but increased flux at optical-to-near-IR wavelengths (due to decreased dust attenuation, in spite of the lowered star formation rate), relative to the case without AGN winds. The FIR half-light radius decreases from ∼1 to $\sim 0.1\, \rm {kpc}$ in $\lesssim 40\, \rm {Myr}$ when AGN winds are not included, but increases to $\sim 2\, \rm {kpc}$ when they are. Interestingly, the half-light radius at optical-NIR wavelengths remains approximately constant over $35\, \rm {Myr}$, for simulations with and without AGN winds. In the case without winds, this occurs despite the rapid compaction, and is due to heavy dust obscuration in the inner regions of the galaxy. This work highlights the importance of forward-modelling when comparing simulated and observed galaxy populations.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1528
Issue No: Vol. 523, No. 2 (2023)
- What boost galaxy mergers in two massive galaxy protoclusters at z =
2.24'-
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Pages: 2422 - 2439
Abstract: ABSTRACTCharacterizing the structural properties of galaxies in high-redshift protoclusters is key to our understanding of the environmental effects on galaxy evolution in the early stages of galaxy and structure formation. In this study, we assess the structural properties of 85 and 87 Hα emission-line candidates (HAEs) in the densest regions of two massive protoclusters, BOSS1244 and BOSS1542, respectively, using the Hubble Space Telescope (HST) H-band imaging data. Our results show a true pair fraction of 22 ± 5 (33 ± 6) per cent in BOSS1244 (BOSS1542), which yields a merger rate of 0.41 ± 0.09 (0.52 ± 0.04) Gyr−1 for massive HAEs with log (M*/M⊙) ≥ 10.3. This rate is 1.8 (2.8) times higher than that of the general fields at the same epoch. Our sample of HAEs exhibits half-light radii and Sérsic indices that cover a broader range than field star-forming galaxies. Additionally, about 15 per cent of the HAEs are as compact as the most massive (log (M*/M⊙) ≳ 11) spheroid-dominated population. These results suggest that the high galaxy density and cold dynamical state (i.e. velocity dispersion of <400 km s−1) are key factors that drive galaxy mergers and promote structural evolution in the two protoclusters. Our findings also indicate that both the local environment (on group scales) and the global environment play essential roles in shaping galaxy morphologies in protoclusters. This is evident in the systematic differences observed in the structural properties of galaxies between BOSS1244 and BOSS1542.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1543
Issue No: Vol. 523, No. 2 (2023)
- Testing multiband (G, GBP, GRP, B, V, and TESS) standard bolometric
corrections by recovering luminosity and radii of 341 host stars-
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Pages: 2440 - 2452
Abstract: ABSTRACTMain-sequence bolometric corrections (BC) and a standard BC–Teff relation are produced for TESS wavelengths using published physical parameters and light ratios from SED models of 209 detached double-lined eclipsing binaries. This and previous five-band (Johnson B, V, Gaia G, GBP, GRP) standard BC–Teff relations are tested by recovering luminosity (L) of the most accurate 341 single host stars (281 MS, 40 subgiants, 19 giants, and one pre-main-sequence). Recovered L of photometry are compared to L from published R and Teff. A very high correlation (R2 = 0.9983) is achieved for this mixed sample. Error histograms of recovered and calculated L show peaks at ∼2 and ∼4 per cent, respectively. The recovered L and the published Teff were then used in $L = 4\pi R^2 \sigma T^4_{\rm eff}$ to predict the standard R of the host stars. Comparison between the predicted and published R of all luminosity classes are found successful with a negligible offset associated with the giants and subgiants. The peak of the predicted R errors is found at 2 per cent, which is equivalent to the peak of the published R errors. Thus, a main-sequence BC–Teff relation could be used in predicting both L and R of a single star at any luminosity class, but this does not mean BC–Teff relations of all luminosity classes are the same because luminosity information could be more constrained by star’s apparent magnitude ξ than its BC since mBol = ξ + BCξ.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1563
Issue No: Vol. 523, No. 2 (2023)
- The foreground transfer function for H i intensity mapping signal
reconstruction: MeerKLASS and precision cosmology applications-
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Pages: 2453 - 2477
Abstract: ABSTRACTBlind cleaning methods are currently the preferred strategy for handling foreground contamination in single-dish H i intensity mapping surveys. Despite the increasing sophistication of blind techniques, some signal loss will be inevitable across all scales. Constructing a corrective transfer function using mock signal injection into the contaminated data has been a practice relied on for H i intensity mapping experiments. However, assessing whether this approach is viable for future intensity mapping surveys, where precision cosmology is the aim, remains unexplored. In this work, using simulations, we validate for the first time the use of a foreground transfer function to reconstruct power spectra of foreground-cleaned low-redshift intensity maps and look to expose any limitations. We reveal that even when aggressive foreground cleaning is required, which causes ${\gt }\, 50~{{\ \rm per\ cent}}$ negative bias on the largest scales, the power spectrum can be reconstructed using a transfer function to within sub-per cent accuracy. We specifically outline the recipe for constructing an unbiased transfer function, highlighting the pitfalls if one deviates from this recipe, and also correctly identify how a transfer function should be applied in an autocorrelation power spectrum. We validate a method that utilizes the transfer function variance for error estimation in foreground-cleaned power spectra. Finally, we demonstrate how incorrect fiducial parameter assumptions (up to ${\pm }100~{{\ \rm per\ cent}}$ bias) in the generation of mocks, used in the construction of the transfer function, do not significantly bias signal reconstruction or parameter inference (inducing ${\lt }\, 5~{{\ \rm per\ cent}}$ bias in recovered values).
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1567
Issue No: Vol. 523, No. 2 (2023)
- Phenomenological power spectrum models for H α emission line galaxies
from the Nancy Grace Roman Space Telescope-
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Pages: 2498 - 2512
Abstract: ABSTRACTThe High Latitude Spectroscopic Survey (HLSS) is the reference baseline spectroscopic survey for NASA’s Nancy Grace Roman Space Telescope, measuring redshifts of ∼10M H α emission line galaxies over a 2000 deg2 footprint at z = 1–2. In this work, we use a realistic Roman galaxy mock catalogue to explore optimal phenomenological modelling of the measured power spectrum. We consider two methods for modelling the redshift-space distortions (Kaiser squashing and another with a window function on β that selects out the coherent radial infall pairwise velocities, $\mathcal {M}_A$ and $\mathcal {M}_B$, respectively), two models for the non-linear impact of baryons that smear the baryon acoustic oscillation signal (a fixed ratio between the smearing scales in the perpendicular and parallel dimensions and another where these smearing scales are kept as free parameters, Pdw(k k*) and Pdw(k Σ⊥, Σ∥), respectively), and two analytical emulations of non-linear growth (one employing the halo model and another formulated from simulated galaxy clustering of a semi-analytical model, $\mathcal {F}_{HM}$ and $\mathcal {F}_{\it SAM}$, respectively). We find that the best model combination employing $\mathcal {F}_{HM}$ is $P_{dw}(k k_*)*\mathcal {F}_{HM}*\mathcal {M}_B$, while the best combination employing $\mathcal {F}_{\it SAM}$ is $P_{dw}(k k_*)*\mathcal {F}_{\it SAM}*\mathcal {M}_B$, which leads to unbiased measurements of cosmological parameters. We compare these to the Effective Field Theory of Large-Scale Structure perturbation theory model PEFT(k Θ), and find that our simple phenomenological models are comparable across the entire redshift range for kmax = 0.25 and 0.3 h Mpc−1. We expect the tools that we have developed to be useful in probing dark energy and testing gravity using Roman in an accurate and robust manner.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1591
Issue No: Vol. 523, No. 2 (2023)
- Searching for single-frame rapid X-ray transients detected with Chandra
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Pages: 2513 - 2518
Abstract: ABSTRACTWe propose a new method to identify rapid X-ray transients observed with focusing telescopes. They could be statistically significant if three or more photons are detected with Chandra in a single CCD frame within a point-spread-function region out of quiescent background. In the Chandra archive, 11 such events are discovered from regions without point-like sources, after discrimination of cosmic rays and background flares and control of false positives. Among them, two are spatially coincident with extended objects in the Milky Way, one with the Small Magellanic Cloud, and another one with M31; the rest have no or a dim optical counterpart (≳20 mag), and are not clustered on the Galactic plane. Possible physical origins of the rapid transients are discussed, including short gamma-ray bursts (GRBs), short-lived hypermassive neutron stars produced by merger of neutron stars, accreting compact objects in the quiescent state, magnetars, and stellar flares. According to the short GRB event rate density, we expect to have detected $2.3_{-0.6}^{+0.7}$ such events in the Chandra archive. This method would also allow us to reveal quiescent black holes with only a few photons.
PubDate: Sat, 27 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1599
Issue No: Vol. 523, No. 2 (2023)
- Observations of the planetary nebula SMP LMC 058 with the JWST MIRI medium
resolution spectrometer-
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Pages: 2519 - 2529
Abstract: ABSTRACTDuring the commissioning of JWST, the medium-resolution spectrometer (MRS) on the mid-infrared instrument (MIRI) observed the planetary nebula SMP LMC 058 in the Large Magellanic Cloud. The MRS was designed to provide medium resolution (R = λ/Δλ) 3D spectroscopy in the whole MIRI range. SMP LMC 058 is the only source observed in JWST commissioning that is both spatially and spectrally unresolved by the MRS and is a good test of JWST’s capabilities. The new MRS spectra reveal a wealth of emission lines not previously detected in this planetary nebula. From these lines, the spectral resolving power (λ/Δλ) of the MRS is confirmed to be in the range R = 4000–1500, depending on the MRS spectral sub-band. In addition, the spectra confirm that the carbon-rich dust emission is from complex hydrocarbons and SiC grains and that there is little to no time evolution of the SiC dust and emission line strengths over a 17-yr epoch. These commissioning data reveal the great potential of the MIRI MRS for the study of circumstellar and interstellar material.
PubDate: Wed, 10 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1609
Issue No: Vol. 523, No. 2 (2023)
- SN 2022ann: a Type Icn supernova from a dwarf galaxy that reveals helium
in its circumstellar environment-
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Pages: 2530 - 2550
Abstract: ABSTRACTWe present optical and near-infrared (NIR) observations of the Type Icn supernova (SN Icn) 2022ann, the fifth member of its newly identified class of SNe. Its early optical spectra are dominated by narrow carbon and oxygen P-Cygni features with absorption velocities of ∼800 km s−1; slower than other SNe Icn and indicative of interaction with a dense, H/He-poor circumstellar medium (CSM) that is outflowing slower than typical Wolf–Rayet wind velocities of >1000 km s−1. We identify helium in NIR spectra 2 weeks after maximum and in optical spectra at 3 weeks, demonstrating that the CSM is not fully devoid of helium. Unlike other SNe Icn, the spectra of SN 2022ann never develop broad features from SN ejecta, including in the nebular phase. Compared to other SNe Icn, SN 2022ann has a low luminosity (o-band absolute magnitude of ∼−17.7), and evolves slowly. The bolometric light curve is well-modelled by 4.8 M⊙ of SN ejecta interacting with 1.3 M⊙ of CSM. We place an upper limit of 0.04 M⊙ of 56Ni synthesized in the explosion. The host galaxy is a dwarf galaxy with a stellar mass of 107.34 M⊙ (implied metallicity of log(Z/Z⊙) ≈ 0.10) and integrated star-formation rate of log (SFR) = −2.20 M⊙ yr−1; both lower than 97 per cent of galaxies observed to produce core-collapse supernovae, although consistent with star-forming galaxies on the galaxy Main Sequence. The low CSM velocity, nickel and ejecta masses, and likely low-metallicity environment disfavour a single Wolf–Rayet progenitor star. Instead, a binary companion is likely required to adequately strip the progenitor and produce a low-velocity outflow.
PubDate: Mon, 15 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1433
Issue No: Vol. 523, No. 2 (2023)
- Impact of systematic nuclear uncertainties on composition and decay heat
of dynamical and disc ejecta in compact binary mergers-
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Pages: 2551 - 2576
Abstract: ABSTRACTTheoretically predicted yields of elements created by the rapid neutron capture (r-)process carry potentially large uncertainties associated with incomplete knowledge of nuclear properties and approximative hydrodynamical modelling of the matter ejection processes. We present an in-depth study of the nuclear uncertainties by varying theoretical nuclear input models that describe the experimentally unknown neutron-rich nuclei. This includes two frameworks for calculating the radiative neutron capture rates and 14 different models for nuclear masses, β-decay rates, and fission properties. Our r-process nuclear network calculations are based on detailed hydrodynamical simulations of dynamically ejected material from NS–NS or NS–BH binary mergers plus the secular ejecta from BH–torus systems. The impact of nuclear uncertainties on the r-process abundance distribution and the early radioactive heating rate is found to be modest (within a factor of ∼20 for individual A > 90 abundances and a factor of 2 for the heating rate). However, the impact on the late-time heating rate is more significant and depends strongly on the contribution from fission. We witness significantly higher sensitivity to the nuclear physics input if only a single trajectory is used compared to considering ensembles with a much larger number of trajectories (ranging between 150 and 300), and the quantitative effects of the nuclear uncertainties strongly depend on the adopted conditions for the individual trajectory. We use the predicted Th/U ratio to estimate the cosmochronometric age of six metal-poor stars and find the impact of the nuclear uncertainties to be up to 2 Gyr.
PubDate: Mon, 15 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1458
Issue No: Vol. 523, No. 2 (2023)
- Collisional excitation of methyl (iso)cyanide by He atoms: rate
coefficients and isomerism effects-
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Pages: 2577 - 2586
Abstract: ABSTRACTAmong all closed-shell species observed in molecular clouds, molecules with C3v symmetry play a crucial role, as their rotational spectroscopy allows them to behave as a gas thermometer. In the interstellar medium, methyl cyanide (CH3CN) is the second most abundant of those (after ammonia, NH3). Its isomer, methyl isocyanide (CH3NC), is less abundant but has been detected in many astrophysical sources. In order to assess their absolute and relative abundances, it is essential to understand their collisional excitation properties. This paper reports the calculation of rate coefficients for rotational excitation of CH3CN and CH3NC molecules with He atoms, from low (5 K) to moderate (100 K) temperatures. We include the first 74 and 66 rotational states of both para and ortho symmetries of CH3CN and CH3NC, respectively. A propensity for Δj = 2 transitions is observed in the case of CH3CN-He collisions, whereas in the case of CH3NC-He a propensity for Δj = 1 is observed for transitions involving low values of j and at low temperatures, a propensity for Δj = 2 is observed for higher values of j and at high temperatures. A comparison of rate coefficients shows differences up to a factor of 3, depending on temperature and on the ortho/para symmetries for dominant transitions. This confirms the importance of having specific collisional data for each isomer. We also examined the effect of these new rates on the CH3CN and CH3NC excitation in molecular clouds by performing radiative transfer calculations of the excitation and brightness temperatures for several detected lines.
PubDate: Wed, 17 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1508
Issue No: Vol. 523, No. 2 (2023)
- An effective model for the cosmic-dawn 21-cm signal
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Pages: 2587 - 2607
Abstract: ABSTRACTThe 21-cm signal holds the key to understanding the first structure formation during cosmic dawn. Theoretical progress over the last decade has focused on simulations of this signal, given the non-linear and non-local relation between initial conditions and observables (21 cm or reionization maps). Here, instead, we propose an effective and fully analytical model for the 21-cm signal during cosmic dawn. We take advantage of the exponential-like behaviour of the local star-formation rate density (SFRD) against densities at early times to analytically find its correlation functions including non-linearities. The SFRD acts as the building block to obtain the statistics of radiative fields (X-ray and Lyman α fluxes), and therefore the 21-cm signal. We implement this model as the public python package Zeus21. This code can fully predict the 21-cm global signal and power spectrum in ∼1 s, with negligible memory requirements. When comparing against state-of-the-art semi-numerical simulations from 21CMFAST we find agreement to $\sim 10~{{\ \rm per\ cent}}$ precision in both the 21-cm global signal and power spectra, after accounting for a (previously missed) underestimation of adiabatic fluctuations in 21CMFAST. Zeus21 is modular, allowing the user to vary the astrophysical model for the first galaxies, and interfaces with the cosmological code CLASS, which enables searches for beyond standard-model cosmology in 21-cm data. This represents a step towards bringing 21-cm to the era of precision cosmology.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1512
Issue No: Vol. 523, No. 2 (2023)
- congruents (COsmic ray, Neutrino, Gamma-ray, and Radio Non-Thermal
Spectra) – I. A predictive model for galactic non-thermal emission-
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Pages: 2608 - 2629
Abstract: ABSTRACTThe total luminosity and spectral shape of the non-thermal emission produced by cosmic rays depends on their interstellar environment, a dependence that gives rise to correlations between galaxies’ bulk properties – star-formation rate, stellar mass, and others – and their non-thermal spectra. Understanding the physical mechanisms of cosmic ray transport, loss, and emission is key to understanding these correlations. Here, in the first paper of the series, we present a new method to compute the non-thermal spectra of star-forming galaxies, and describe an open-source software package – congruents(COsmic ray, Neutrino, Gamma-ray, and Radio Non-Thermal Spectra) – that implements it. As a crucial innovation, our method requires as input only a galaxy’s effective radius, star-formation rate, stellar mass, and redshift, all quantities that are readily available for large samples of galaxies and do not require expensive, spatially resolved gas measurements. From these inputs we derive individual, galaxy-by-galaxy models for the background gas and radiation field through which cosmic rays propagate, from which we compute steady-state cosmic ray spectra for hadronic and leptonic particles in both the galactic disc and halo by solving the full kinetic equation. We invoke modern models for cosmic ray transport and include all significant emission and loss mechanisms. In this paper, we describe the model and validate it against non-thermal emission measured in nearby star-forming galaxies that span four orders of magnitude in star-formation rate.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1524
Issue No: Vol. 523, No. 2 (2023)
- Distinguishing magnetized disc winds from turbulent viscosity through
substructure morphology in planet-forming discs-
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Pages: 2630 - 2640
Abstract: ABSTRACTThe traditional paradigm of viscosity-dominated evolution of protoplanetary discs has been recently challenged by existence of magnetized disc winds. However, distinguishing wind-driven and turbulence-driven accretion through observations has been difficult. In this study, we present a novel approach to identifying their separate contribution to angular momentum transport by studying the gap and ring morphology of planet-forming discs in the ALMA continuum. We model the gap-opening process of planets in discs with both viscous evolution and wind-driven accretion by 2D multifluid hydrodynamical simulations. Our results show that gap-opening planets in wind-driven accreting discs generate characteristic dust substructures that differ from those in purely viscous discs. Specifically, we demonstrate that discs where wind-driven accretion dominates the production of substructures exhibit significant asymmetries. Based on the diverse outputs of mock images in the ALMA continuum, we roughly divide the planet-induced features into four regimes (moderate-viscosity dominated, moderate-wind dominated, strong-wind dominated, and inviscid). The classification of these regimes sets up a potential method to constrain the strength of magnetized disc wind and viscosity based on the observed gap and ring morphology. We discuss the asymmetry feature in our mock images and its potential manifestation in ALMA observations.
PubDate: Tue, 23 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1553
Issue No: Vol. 523, No. 2 (2023)
- The value-added catalogue of ASAS-SN eclipsing binaries – III. Masses
and radii of Gaia spectroscopic binaries-
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Pages: 2641 - 2650
Abstract: ABSTRACTMasses and radii of stars can be derived by combining eclipsing binary light curves with spectroscopic orbits. In our previous work, we modelled the All-Sky Automated Survey for Supernovae (ASAS-SN) light curves of more than 30 000 detached eclipsing binaries using phoebe. Here, we combine our results with 128 double-lined spectroscopic orbits from Gaia Data Release 3. We also visually inspect ASAS-SN light curves of the Gaia double-lined spectroscopic binaries on the lower main sequence and the giant branch, adding 11 binaries to our sample. We find that only 50 per cent of systems have Gaia periods and eccentricities consistent with the ASAS-SN values. We use emcee and phoebe to determine masses and radii for a total of 122 stars with median fractional uncertainties of 7.9 per cent and 6.3 per cent, respectively.
PubDate: Sat, 27 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1560
Issue No: Vol. 523, No. 2 (2023)
- Dynamical evolution of the resistive thick accretion Tori around a
Schwarzschild black hole-
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Pages: 2651 - 2662
Abstract: ABSTRACTTo study time-dependent phenomena of plasma surrounding a non-rotating black hole with a dipolar magnetic field, we have developed a fully set of 3 + 1 formalism of generalized general relativistic magnetohydrodynamic equations. The general relativistic phenomena, in particular, have been investigated with respect to the Ohm law. Magnetofluid is supposed to flow in three directions and forms a thick disc structure around the central black hole. All physical quantities of the system are functions of three variables: radial distance r, polar angle θ, and time t. The radial, meridional, and time behaviours of all these quantities have been investigated. It has been shown that the electrical conductivity of the fluid is not constant and may be both positive and negative depending on the values of some free parameters. The initially purely rotating non-magnetized plasma in the presence of an external magnetic field gives rise to an azimuthal current density and a charge density measured by the comoving observer. This current generates an electromagnetic field inside the disc which has both poloidal and toroidal components. The dipolar magnetic field lines of the central black hole is able to penetrate the plasma disc, due to the presence of a finite resistivity for the plasma. The accreting plasma pushes them outwards and makes them parallel to the rotation axis of the disc in the meridional plane.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1562
Issue No: Vol. 523, No. 2 (2023)
- Detection of the free precession period of the accreting neutron star in
4U 1820–30-
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Pages: 2663 - 2677
Abstract: ABSTRACTDetection of free precession is very important for analysing the internal structure of neutron stars. So far, because of the interference of the accretion process, no feasible method has been proposed to detect the precession of accreting neutron stars in both theory and observations. Based on the analysis of archive data from Chandra and the Neutron Star Interior Composition ExploreR (NICER) of the ultra-compact X-ray binary system 4U 1820–30, we find that the energy spectra have a stable sinusoidal bi-directional oscillation period near 1000 s, no matter which state the X-ray binary system is in. After we fit the energy spectra and carry out Fourier decomposition of the fitting parameters, we find that this period is more steadily emitted from the neutron star. We discuss the possible origin of this period and conclude that the period is most likely the free precession period of the neutron star in 4U 1820–30. Its nutation can result in the seesaw-like periodical bi-directional oscillation we find in this paper.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1566
Issue No: Vol. 523, No. 2 (2023)
- Aerosol parameters for night sky brightness modelling estimated from
daytime sky images-
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Pages: 2678 - 2683
Abstract: ABSTRACTAtmospheric turbidity is one of the key factors influencing the propagation of artificial light into the environment during cloudless nights. High aerosol loading can reduce the visibility of astronomical objects, and thus information on atmospheric pollution is critical for the prediction of the night sky brightness (NSB) distribution. In particular, the aerosol optical depth (AOD) and asymmetry parameter (g) are among the most important aerosol properties influencing the NSB amplitudes. However, these two parameters are rarely available at astronomical sites. Here, we develop a method for AOD and g retrievals from clear-sky radiometry carried out around sunset or sunrise, shortly before or after night-time observation is intended. The method allows for reducing the number of unknowns needed in the processing and interpretation of night sky radiances, and thus provides an efficient tool for gathering input data to present skyglow simulators. The practice of collecting information about aerosols in this way could become a routine part of astronomical observations, much like observing standard stars to obtain extinction coefficients. If the procedure were conducted around sunset and the data were quickly reduced, it could offer an on-the-spot estimate of the NSB for the night ahead. The error analysis is performed using the theoretical model, while taking into account experimental errors of radiance readings. The capability of the method is demonstrated in a field experiment conducted under cloudless conditions.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1570
Issue No: Vol. 523, No. 2 (2023)
- Radiative association of P+(3P) and O(3P) for the PO+ formation
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Pages: 2684 - 2692
Abstract: ABSTRACTPhosphorus (P) is essential for the development of life since it is a fundamental element in many important biological molecules. Due to its biogenic importance, many astrochemists have begun to investigate the possibility of the phosphorus-bearing species formed in interstellar environments. Radiative association (RA) is a possible way for the formation of the phosphorus monoxide ion (PO+) in interstellar and related environments. Laboratory measurements are almost impossible to carry out, so theoretical calculations are essential for investigating such formation mechanism of PO+. The quantum mechanical method is used to obtain its cross sections and rate coefficients. Thirty contributing processes for the computation of the total rate coefficient are considered, including 22 transition dipole processes and eight permanent dipole processes. The total rate coefficient varies little over the entire temperature range of 1–10 000 K and its magnitude is of the order of (4–8) × 10−17 cm3 s−1. The 2 1Σ+ → X 1Σ+ transition process dominates the formation of PO+ by RA over the entire temperature range considered here. The C 1Π → X 1Σ+ and 2 3Σ+ → a 3Σ+ are also relatively important, but their rate coefficients are about an order of magnitude smaller than that of the 2 1Σ+ → X 1Σ+ channel. The obtained cross sections and rate coefficient can be used to model the P astrochemistry in the interstellar medium.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1571
Issue No: Vol. 523, No. 2 (2023)
- Galaxy And Mass Assembly (GAMA): The group H i mass as a function of
halo mass-
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Pages: 2693 - 2709
Abstract: ABSTRACTWe determine the atomic hydrogen (H i) to halo mass relation (HIHM) using Arecibo Legacy Fast ALFA survey H i data at the location of optically selected groups from the Galaxy And Mass Assembly (GAMA) survey. We make direct H i detections for 37 GAMA groups. Using H i group spectral stacking of 345 groups, we study the group H i content as a function of halo mass across a halo mass range of 1011–1014.7 M⊙. We also correct our results for Eddington bias. We find that the group H i mass generally rises as a function of halo mass from 1.3% of the halo mass at $10^{11.6} \, \text{M}_\odot$ to 0.4% at $10^{13.7} \, \text{M}_\odot$ with some indication of flattening towards the high-mass end. Despite the differences in optical survey limits, group catalogues, and halo mass estimation methods, our results are consistent with previous group H i-stacking studies. Our results are also consistent with mock observations from shark and IllustrisTNG.
PubDate: Fri, 26 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1575
Issue No: Vol. 523, No. 2 (2023)
- Meteor cluster event indication in variable-length astronomical video
sequences-
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Pages: 2710 - 2720
Abstract: ABSTRACTIn recent years, the study of parallel or cluster meteor events has become increasingly popular. Many imaging systems currently focus on meteor detection, but the algorithms exploiting the data from such systems do not investigate the probability of cluster or parallel meteor events. This paper presents a novel approach to indicate a potential meteor cluster or parallel meteor event based on variable-length astronomical video sequences. The presented algorithm consists of two main parts: meteor event pre-detection and meteor cluster event probability evaluation. The first part of the algorithm involves a meteor pre-detection method based on the Hough transform and the exact event location within the time domain. In addition to pre-detecting meteor events, the method outputs event trajectory parameters that are further exploited in a second part of the algorithm. This subsequent part of the algorithm then operates over these meteor trajectory parameters and indicates the probability of cluster occurrence. The algorithm is experimentally evaluated on video sequences generated by the Meteor Automatic Imager and Analyzer (MAIA) astronomical imaging system, covering the Draconid and September ϵ Perseid meteor showers. Compared to the current MAIA meteor detection software, the proposed part of the pre-detection algorithm shows promising results, especially the increased rate of correct meteor detection. The meteor cluster evaluation part of the algorithm then demonstrates its ability to successfully select related meteor event candidates (disintegrated from the same parental object) and reject unrelated ones.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1578
Issue No: Vol. 523, No. 2 (2023)
- Nuclear star clusters as probes of dark matter haloes: the case of the
Sagittarius dwarf spheroidal galaxy-
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Pages: 2721 - 2731
Abstract: ABSTRACTThe Sagittarius dwarf spheroidal (Sgr dSph) galaxy is currently being accreted and disrupted by the tidal field of the Milky Way. Recent observations have shown that the central region of the dwarf hosts at least three different stellar populations, ranging from old and metal-poor over intermediate metal-rich to young metal-rich. While the intermediate-age metal-rich population has been identified as part of the galaxy, the oldest and youngest populations belong to M54, the nuclear star cluster (NSC) of the Sgr dSph galaxy. The old metal-poor component of M54 has been interpreted as at least one decayed globular cluster (GC) that was initially orbiting its host galaxy. The youngest population formed in situ from gas accreted into M54 after its arrival at the centre of the host. In this work, we use the observed properties of M54 to explore the shape of the inner density profile of the Sgr dSph galaxy. To do so, we simulate the decay of M54 towards the centre of the dark matter (DM) halo of its host. We model the DM density profile using different central slopes, and we compare the results of the simulations to the most recent observations of the structural properties of M54. From this comparison, we conclude that a GC that decays in a DM halo with a density profile ∝ r−γ and γ ≤ 1 shows a rotational signal and flattening comparable to those observed for M54. Steeper profiles produce, instead, highly rotating and more flattened NSCs which do not match the properties of M54.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1584
Issue No: Vol. 523, No. 2 (2023)
- Tidal capture of an asteroid by a magnetar: FRB-like bursts, glitch, and
antiglitch-
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Pages: 2732 - 2737
Abstract: ABSTRACTRecently, remarkable antiglitch and glitch accompanied by bright radio bursts of the Galactic magnetar SGR J1935+2154 were discovered. These two infrequent temporal coincidences between the glitch/antiglitch and the fast radio burst (FRB)-like bursts reveal their physical connection of them. Here, we propose that the antiglitch/glitch and FRB-like bursts can be well understood by an asteroid tidally captured by a magnetar. In this model, an asteroid is tidally captured and disrupted by a magnetar. Then, the disrupted asteroid will transfer the angular momentum to the magnetar producing a sudden change in the magnetar rotational frequency at the magnetosphere radius. If the orbital angular momentum of the asteroid is parallel (or antiparallel) to that of the spinning magnetar, a glitch (or antiglitch) will occur. Subsequently, the bound asteroid materials fall back to the pericentre and eventually are accreted to the surface of the magnetar. Massive fragments of the asteroid cross magnetic field lines and produce bright radio bursts through coherent curvature radiation. Our model can explain the sudden magnetar spin changes and FRB-like bursts in a unified way.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1585
Issue No: Vol. 523, No. 2 (2023)
- The relationship between cluster environment and molecular gas content of
star-forming galaxies in the eagle simulation-
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Pages: 2738 - 2758
Abstract: ABSTRACTWe employ the eagle hydrodynamical simulation to uncover the relationship between cluster environment and H2 content of star-forming galaxies at redshifts spanning 0 ≤ z ≤ 1. To do so, we divide the star-forming sample into those that are bound to clusters and those that are not. We find that, at any given redshift, the galaxies in clusters generally have less H2 than their non-cluster counterparts with the same stellar mass (corresponding to an offset of ≲0.5 dex), but this offset varies with stellar mass and is virtually absent at M⋆ ≲ 109.3 M⊙. The H2 deficit in star-forming cluster galaxies can be traced back to a decline in their H2 content that commenced after first infall into a cluster, which occurred later than a typical cluster galaxy. Evolution of the full cluster population after infall is generally consistent with ‘slow-then-rapid’ quenching, but galaxies with M⋆ ≲ 109.5 M⊙ exhibit rapid quenching. Unlike most cluster galaxies, star-forming ones were not pre-processed in groups prior to being accreted by clusters. For both of these cluster samples, the star formation efficiency remained oblivious to the infall. We track the particles associated with star-forming cluster galaxies and attribute the drop in H2 mass after infall to poor replenishment, depletion due to star formation, and stripping of H2 in cluster environments. These results provide predictions for future surveys, along with support and theoretical insights for existing molecular gas observations that suggest there is less H2 in cluster galaxies.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1587
Issue No: Vol. 523, No. 2 (2023)
- Exploring the centre of mass properties of LG-like galaxies
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Pages: 2759 - 2769
Abstract: ABSTRACTFrom high resolution cosmological simulations of the Local Group in a realistic environment, namely HESTIA simulations, we study the position and kinematic deviations that may arise between the disc of a Milky Way (or Andromeda)-like galaxy and its halo. We focus on the three-dimensional analysis of the centres of mass (COM). The study presents two parts. We first consider individual particles to track down the nature and amplitude of the physical deviations of the COM with respect to the distance from the disc centre. Dark matter dominates the behaviour of the COM of all particles at all distances. But the total COM is also very close to the COM of stars. In the absence of a significant merger, the velocity offsets are marginal (10 km s−1) but the positional shifts can be important compared to the disc characteristics (>10 kpc). In the event of a massive accretion, discrepancies are of the same order as the recent finding for the MW under the Magellanic Clouds influence. In a second part, the accent is put on the study of various populations of subhaloes and satellites. We show that satellites properly represent the entire subhalo population. There exists strong mismatch in phase space between the satellites’ COM and the host disc. Moreover, the results are highly inhomogeneous between the simulations and thus, between the accretion histories. Finally, we point out that these shifts are mainly due to a few of the most massive objects.
PubDate: Sat, 27 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1598
Issue No: Vol. 523, No. 2 (2023)
- Origins of the shocks in high-mass starless clump candidates
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Pages: 2770 - 2787
Abstract: ABSTRACTShocks are abundant in star-forming regions, and are often related with star formation. In our previous observations toward 100 starless clump candidates (SCCs) in the Galaxy, a sample of 34 SCCs associated with shocks is identified. In this work, we perform mapping observations of the SiO 2–1, 3–2, HC3N 10–9, HCO+ 1–0, H13CO+ 1–0, and H41 α lines toward 9 out of the detected sources by using IRAM 30-m radio telescope to study the origins of the shocks in the SCCs. We find shocks in three sources (BGPS 3110, 3114, and 3118) are produced by collisions between the expanding ionized gas and ambient molecular gas, instead of by the star formation activity inside SCCs. On the other hand, shocks in the other six sources are related to star formation activity of SCCs. The signatures of protostellar outflows are clearly shown in the molecular lines toward BGPS 4029, 4472, 5064. Comparing our results with the previous ALMA observations performed in the same region, the shocks in BGPS 3686 and 5114 are also likely to be due to protostellar activity. The origin of shock in BGPS 5243 is still unclear although some features in the SiO spectra imply the presence of protostellar activity.
PubDate: Mon, 29 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1604
Issue No: Vol. 523, No. 2 (2023)
- Broad-band spectro-temporal investigation of neutron star low-mass X-ray
binary GX 349+2-
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Pages: 2788 - 2806
Abstract: ABSTRACTWe report a broad-band investigation of the Z-type neutron star (NS) low mass X-ray binary (LMXB) GX 349+2 using AstroSat and Neutron star Interior Composition Explorer (NICER). AstroSat observed the source exhibiting large scale variability in its normal branch (NB)/flaring branch (FB) vertex and FB and a moderate evolution during NICER observations. The power spectra exhibit very low-frequency noise (VLFN) and low-frequency noise (LFN)/FB noise, described by a power law (PL) and an evolving Lorentzian. We investigate the energy dependence of variability components and their correlation with the spectral state to probe their origin. The joint spectra of GX 349+2 are modeled by two thermal and one non-thermal component. The source moves along the Z track, with the increasing accretion rate, further heating of the NS boundary layer (BL), and increasing temperature/radius of the brightened hotspot at the disc-BL interface/NS surface. A PL well represents the hard non-thermal coronal emission. As predicted by the gravitational redshift, we find a correlation between the line energy detected in NICER spectra and the inner disc radius with the Spearman rank correlation coefficient of 1. Using this correlation, we demonstrate the potential of a method to constrain the accreting compact object properties, including evolving continuum and line spectroscopy. We report the first detection of hard lag providing evidence of the VLFN originating from the accretion disc in NS LMXBs, representing fluctuation of propagation through the disc.
PubDate: Sat, 27 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1606
Issue No: Vol. 523, No. 2 (2023)
- Correction to: Instabilities in dusty non-isothermal protoplanetary discs
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Pages: 2807 - 2808
Abstract: This is a correction to: M. Lehmann, M.-K. Lin, Instabilities in dusty non-isothermal protoplanetary discs, Monthly Notices of the Royal Astronomical Society, Volume 522, Issue 4, July 2023, Pages 5892–5930, https://doi.org/10.1093/mnras/stad1349.
PubDate: Tue, 06 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1607
Issue No: Vol. 523, No. 2 (2023)
- Scattering transparency of clouds in exoplanet transit spectra
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Pages: 2809 - 2817
Abstract: ABSTRACTThe presence of aerosols in an exoplanet atmosphere can veil the underlying material and can lead to a flat transmission spectrum during primary transit observations. In this work, we explore forward scattering effects from supermicron-sized aerosol particles present in the atmosphere of a transiting exoplanet. We find that the impacts of forward scattering from larger aerosols can significantly impact exoplanet transits and the strength of these effects can be dependent on wavelength. In certain cloud configurations, the forward-scattered light can effectively pass through the clouds unhindered, thus rendering the clouds transparent. The dependence of the aerosol scattering properties on wavelength can then lead to a positive slope in the transit spectrum. These slopes are characteristically different from both Rayleigh and aerosol absorption slopes. As examples, we demonstrate scattering effects for both a rocky world and a hot Jupiter. In these models, the predicted spectral slopes due to forward-scattering effects can manifest in the transit spectrum at the level of ∼10–∼100 s of parts per million and, hence, could be observable with NASA’s JWST.
PubDate: Mon, 29 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1610
Issue No: Vol. 523, No. 2 (2023)
- Resolving a merger in a hyperluminous submillimeter galaxy at
z = 2.82-
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Pages: 2818 - 2831
Abstract: ABSTRACTWe present the resolved properties of the z = 2.82 hyperluminous infrared Galaxy (HyLIRG) HS1700.850.1, the brightest 850 $\mu$m source found in the SCUBA-2 followup to the Keck Baryonic Structure Survey fields (S850$\mu$m =19.5 mJy), and amongst the most luminous starbursts known at any redshift.- Using the IRAM-NOEMA interferometer in the highest resolution A-configuration, we resolve the source into two components separated by ∼8 kpc, visible as blue shifted and red shifted 12CO(5–4) lines, exhibiting the expected kinematic properties of a major merger between two gas rich Galaxies. The combined merger system is traced over 2.3 arcsec or 18.4 kpc. Each component of the merger shows ordered gas motions suggestive of a massive turbulent disc. We measure the dynamical masses of the blue and red discs as (1.5 ± 0.2) × 1011 and (0.71 ± 0.22) × 1011 M⊙, respectively. The more massive disc component shows broad wings in the CO line, offset by ∼3 kpc from the disc centroid along the major axis, and extending to velocities ∼±1000 km $\rm {s^{-1}}$ from systemic velocity. We interpret this as either a possible bipolar outflowing component, or more likely a warping or tidal structure in the CO disc. Comparing the properties of HS1700.850.1 to other submillimeter detected galaxies with comparably bright 850 $\mu$m luminosities suggests that ongoing gas-rich mergers, or at least a clustered/group environment lead to these most extreme starburst phases.
PubDate: Sat, 27 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1613
Issue No: Vol. 523, No. 2 (2023)
- Eccentricity growth of massive planets inside cavities of protoplanetary
discs-
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Pages: 2832 - 2849
Abstract: ABSTRACTWe carry out hydrodynamical simulations to study the eccentricity growth of a 1–30 Jupiter mass planet located inside the fixed cavity of a protoplanetary disc. The planet exchanges energy and angular momentum with the disc at resonant locations, and its eccentricity grows due to Lindblad resonances. We observe several phases of eccentricity growth where different eccentric Lindblad resonances dominate from 1:3 up to 3:5. The maximum values of eccentricity reached in our simulations are 0.65–0.75. We calculate the eccentricity growth rate for different planet masses and disc parameters and derive analytical dependencies on these parameters. We observe that the growth rate is proportional to both the planet’s mass and the characteristic disc mass for a wide range of parameters. In a separate set of simulations, we derived the width of the 1:3 Lindblad resonance.
PubDate: Fri, 02 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad987
Issue No: Vol. 523, No. 2 (2023)
- MeerKAT caught a Mini Mouse: serendipitous detection of a young radio
pulsar escaping its birth site-
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Pages: 2850 - 2857
Abstract: ABSTRACTIn MeerKAT observations pointed at a Galactic X-ray binary located on the Galactic plane, we serendipitously discovered a radio nebula with cometary-like morphology. The feature, which we named ‘the Mini Mouse’ based on its similarity with the previously discovered ‘Mouse’ nebula, points back towards the previously unidentified candidate supernova remnant G45.24+0.18. We observed the location of the Mini Mouse with MeerKAT in two different observations, and we localized with arcsecond precision the 138-ms radio pulsar PSR J1914+1054g, recently discovered by the FAST telescope, to a position consistent with the head of the nebula. We confirm a dispersion measure of about 418 pc cm−3 corresponding to a distance between 7.8 and 8.8 kpc based on models of the electron distribution. Using our accurate localization and two period measurements spaced 90 d apart, we calculate a period derivative of (2.7 ± 0.3) × 10 −14 s s−1. We derive a characteristic age of approximately 82 kyr and a spin-down luminosity of 4 × 1035 erg s−1. For a pulsar age comparable with the characteristic age, we find that the projected velocity of the neutron star is between 320 and 360 km s−1 if it was born at the location of the supernova remnant. The size of the proposed remnant appears small if compared with the pulsar characteristic age; however, the relatively high density of the environment near the Galactic plane could explain a suppressed expansion rate and thus a smaller remnant.
PubDate: Fri, 12 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1438
Issue No: Vol. 523, No. 2 (2023)
- Chemical evolution of electron-bombarded crystalline water ices at
different temperatures using the procoda code-
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Pages: 2858 - 2875
Abstract: Water ices are a common component of cold space environments, including molecular and protostellar clouds, and the frozen surfaces of moons, planets, and comets. When exposed to ionizing and/or thermal processing, they become a nursery for new molecular species and are also responsible for their desorption to the gas-phase. Crystalline water ice, produced by the deposition of gaseous water at warm (80–150 K) surfaces or by the heating of cold amorphous water ice (up to ∼150 K), is also regularly detected by astronomical observations. Here, we employed the procoda code to map the chemical evolution of 5 keV electron-bombarded crystalline water-ices at different temperatures (12, 40, 60 and 90 K). The chemical network considered a total of 61 coupled reactions involving nine different chemical species within the ice. Among the results, we observe that the average calculated effective rate constants for radiation-induced dissociation decrease as the ice´s temperature increases. The abundance of molecular species in the ice at chemical equilibrium and its desorption to gas-phase depend on both the temperature of the ice. H2O molecules are the dominant desorbed species, with a desorption yield of about 1 molecule per 100 electrons, which seems to be enhanced for warmer crystalline ices. The obtained results can be employed in astrochemical models to simulate the chemical evolution of interstellar and planetary environments. These findings have implications for astrochemistry and astrobiology, providing insight into crucial chemical processes and helping us understand the chemistry in cold regions in space.
PubDate: Fri, 19 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1518
Issue No: Vol. 523, No. 2 (2023)
- A search for tryptophan in the gas of the IC 348 star cluster of the
Perseus molecular cloud-
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Pages: 2876 - 2886
Abstract: ABSTRACTWe have used spectra of the Spitzer Space Telescope to conduct a search for the aromatic amino acid tryptophan in the interstellar gas of the young star cluster IC 348. For all the strongest mid-infrared (mid-IR) laboratory bands of tryptophan, we have found counterpart emission lines in the observed spectrum which are consistent in wavelength and strength with the laboratory measurements. Assuming that the detected emission lines are due to tryptophan and using the measured fluxes, we estimate a tryptophan column density in the line of sight of the core of IC 348 in the range 109–1011 cm−2. The observed emission lines are also found in the combined spectrum of >30 interstellar locations obtained in diverse unrelated star-forming regions observed by Spitzer. This could be an indication that the molecule causing the emission is widespread in interstellar space. Future high spectral resolution mid-IR searches for proteinogenic amino acids in protostars, protoplanetary discs, and in the interstellar medium will be key to study an exogenous origin of meteoritic amino acids and to understand how the pre-biotic conditions for life were set in the early Earth.
PubDate: Mon, 22 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1535
Issue No: Vol. 523, No. 2 (2023)
- Rotation-tunnelling spectrum and astrochemical modelling of dimethylamine,
CH3NHCH3, and searches for it in space-
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Pages: 2887 - 2917
Abstract: ABSTRACTMethylamine has been the only simple alkylamine detected in the interstellar medium for a long time. With the recent secure and tentative detections of vinylamine and ethylamine, respectively, dimethylamine has become a promising target for searches in space. Its rotational spectrum, however, has been known only up to 45 GHz until now. Here we investigate the rotation-tunnelling spectrum of dimethylamine in selected regions between 76 and 1091 GHz using three different spectrometers in order to facilitate its detection in space. The quantum number range is extended to J = 61 and Ka = 21, yielding an extensive set of accurate spectroscopic parameters. To search for dimethylamine, we refer to the spectral line survey ReMoCA carried out with the Atacama Large Millimeter/submillimeter Array towards the high-mass star-forming region Sagittarius B2(N) and a spectral line survey of the molecular cloud G+0.693–0.027 employing the IRAM 30 m and Yebes 40 m radio telescopes. We report non-detections of dimethylamine towards the hot molecular cores Sgr B2(N1S) and Sgr B2(N2b) as well as G+0.693−0.027 which imply that dimethylamine is at least 14, 4.5, and 39 times less abundant than methylamine towards these sources, respectively. The observational results are compared to computational results from a gas-grain astrochemical model. The modelled methylamine to dimethylamine ratios are compatible with the observational lower limits. However, the model produces too much ethylamine compared with methylamine which could mean that the already fairly low levels of dimethylamine in the models may also be too high.
PubDate: Tue, 23 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1549
Issue No: Vol. 523, No. 2 (2023)
- Fuelling the nuclear ring of NGC 1097
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Pages: 2918 - 2927
Abstract: ABSTRACTGalactic bars can drive cold gas inflows towards the centres of galaxies. The gas transport happens primarily through the so-called bar dust lanes, which connect the galactic disc at kpc scales to the nuclear rings at hundreds of pc scales much like two gigantic galactic rivers. Once in the ring, the gas can fuel star formation activity, galactic outflows, and central supermassive black holes. Measuring the mass inflow rates is therefore important to understanding the mass/energy budget and evolution of galactic nuclei. In this work, we use CO datacubes from the PHANGS-ALMA survey and a simple geometrical method to measure the bar-driven mass inflow rate on to the nuclear ring of the barred galaxy NGC 1097. The method assumes that the gas velocity in the bar lanes is parallel to the lanes in the frame co-rotating with the bar, and allows one to derive the inflow rates from sufficiently sensitive and resolved position–position–velocity diagrams if the bar pattern speed and galaxy orientations are known. We find an inflow rate of $\dot{M}=(3.0 \pm 2.1)\, \rm M_\odot \, yr^{-1}$ averaged over a time span of 40 Myr, which varies by a factor of a few over time-scales of ∼10 Myr. Most of the inflow appears to be consumed by star formation in the ring, which is currently occurring at a star formation rate (SFR) of $\simeq\!1.8\!-\!2 \, \rm M_\odot \, yr^{-1}$, suggesting that the inflow is causally controlling the SFR in the ring as a function of time.
PubDate: Tue, 23 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1554
Issue No: Vol. 523, No. 2 (2023)
- The effect of noise artefacts on gravitational-wave searches for neutron
star post-merger remnants-
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Pages: 2928 - 2933
Abstract: ABSTRACTGravitational waves from binary neutron star post-merger remnants have the potential to uncover the physics of the hot nuclear equation of state. These gravitational-wave signals are high frequency (∼kHz) and short-lived ($\mathcal {O}(10\, \mathrm{ms})$), which introduces potential problems for data analysis algorithms due to the presence of non-stationary and non-Gaussian noise artefacts in gravitational-wave observatories. We quantify the degree to which these noise features in LIGO data may affect our confidence in identifying post-merger gravitational-wave signals. We show that the combination of vetoing data with non-stationary glitches and the application of the Allen χ2 veto (usually reserved for long-lived lower frequency gravitational-wave signals), allows one to confidently detect post-merger signals with signal-to-noise ratio ρ ≳ 8. We discuss the need to incorporate the data quality checks and vetoes into realistic post-merger gravitational-wave searches, and describe their relevance to calculating realistic false-alarm and false-dismissal rates.
PubDate: Tue, 23 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1556
Issue No: Vol. 523, No. 2 (2023)
- Density biases and temperature relations for DESIRED H ii regions
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Pages: 2952 - 2973
Abstract: ABSTRACTWe present a first study based on the analysis of the DEep Spectra of Ionized REgions Data base (DESIRED). This is a compilation of 190 high signal-to-noise ratio optical spectra of $\mathrm{H\, \scriptstyle II}$ regions and other photoionized nebulae, mostly observed with 8–10 m telescopes and containing ∼29 380 emission lines. We find that the electron density –ne– of the objects is underestimated when [$\mathrm{S\, \scriptstyle II}$] λ6731/λ6716 and/or [$\mathrm{O\, \scriptstyle II}$] λ3726/λ3729 are the only density indicators available. This is produced by the non-linear density dependence of the indicators in the presence of density inhomogeneities. The average underestimate is ∼300 cm−3 in extragalactic $\mathrm{H\, \scriptstyle II}$ regions, introducing systematic overestimates of Te([$\mathrm{O\, \scriptstyle II}$]) and Te([$\mathrm{S\, \scriptstyle II}$]) compared to Te([$\mathrm{N\, \scriptstyle II}$]). The high-sensitivity of [$\mathrm{O\, \scriptstyle II}$] λλ7319 + 20 + 30 + 31/λλ3726 + 29 and [$\mathrm{S\, \scriptstyle II}$] λλ4069 + 76/λλ6716 + 31 to density makes them more suitable for the diagnosis of the presence of high-density clumps. If Te([$\mathrm{N\, \scriptstyle II}$]) is adopted, the density underestimate has a small impact in the ionic abundances derived from optical spectra, being limited to up to ∼0.1 dex when auroral [$\mathrm{S\, \scriptstyle II}$] and/or [$\mathrm{O\, \scriptstyle II}$] lines are used. However, these density effects are critical for the analysis of infrared fine structure lines, such as those observed by the JWST in local star forming regions, implying strong underestimates of the ionic abundances. We present temperature relations between Te([$\mathrm{O\, \scriptstyle III}$]), Te([$\mathrm{Ar\, \scriptstyle III}$]), Te([$\mathrm{S\, \scriptstyle III}$]), and Te([$\mathrm{N\, \scriptstyle II}$]) for the extragalactic $\mathrm{H\, \scriptstyle II}$ regions. We confirm a non-linear dependence between Te([$\mathrm{O\, \scriptstyle III}$]) and Te([$\mathrm{N\, \scriptstyle II}$]) due to a more rapid increase of Te([$\mathrm{O\, \scriptstyle III}$]) at lower metallicities.
PubDate: Wed, 24 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1569
Issue No: Vol. 523, No. 2 (2023)
- Origin of neutron-capture elements with the Gaia-ESO survey: the evolution
of s- and r-process elements across the Milky Way-
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Pages: 2974 - 2989
Abstract: ABSTRACTWe investigate the origin of neutron-capture elements by analysing their abundance patterns and radial gradients in the Galactic thin disc. We adopt a detailed two-infall chemical evolution model for the Milky Way, including state-of-the-art nucleosynthesis prescriptions for neutron-capture elements. We consider r-process nucleosynthesis from merging neutron stars (MNS) and magneto-rotational supernovae (MR-SNe), and s-process synthesis from low- and intermediate-mass stars (LIMS) and rotating massive stars. The predictions of our model are compared with data from the sixth data release of the Gaia-ESO survey, from which we consider 62 open clusters with age ≳ 0.1 Gyr and ∼1300 Milky Way disc field stars. We conclude that: (i) the [Eu/Fe] versus [Fe/H] diagram is reproduced by both prompt and delayed sources, with the prompt source dominating Eu production; (ii) rotation in massive stars significantly contributes to the first peak s-process elements, but MNS and MR-SNe are necessary to match the observations; and (iii) our model slightly underpredicts Mo and Nd, while accurately reproducing the [Pr/Fe] versus [Fe/H] trend. Regarding the radial gradients, we find that: (i) our predicted [Fe/H] gradient slope agrees with observations from Gaia-ESO and other high-resolution spectroscopic surveys; (ii) the predicted [Eu/H] radial gradient slope is steeper than the observed one, regardless of how quick the production of Eu is, prompting discussion on different Galaxy-formation scenarios and stellar radial migration effects; and (iii) elements in the second s-process peak as well as Nd and Pr exhibit a plateau at low-Galactocentric distances, likely due to enhanced enrichment from LIMS in the inner regions.
PubDate: Fri, 26 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1577
Issue No: Vol. 523, No. 2 (2023)
- Impact of jets on kilonova photometric and polarimetric emission from
binary neutron star mergers-
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Pages: 2990 - 3000
Abstract: ABSTRACTA merger of binary neutron stars creates heavy unstable elements whose radioactive decay produces a thermal emission known as a kilonova. In this paper, we predict the photometric and polarimetric behaviour of this emission by performing 3D Monte Carlo radiative transfer simulations. In particular, we choose three hydrodynamical models for merger ejecta, two including jets with different luminosities and one without a jet structure, to help decipher the impact of jets on the light curve and polarimetric behaviour. In terms of photometry, we find distinct colour evolutions across the three models. Models without a jet show the highest variation in light curves for different viewing angles. In contrast to previous studies, we find models with a jet to produce fainter kilonovae when viewed from orientations close to the jet axis, compared to a model without a jet. In terms of polarimetry, we predict relatively low levels (≲0.3–0.4 per cent) at all orientations that, however, remain non-negligible until a few days after the merger and longer than previously found. Despite the low levels, we find that the presence of a jet enhances the degree of polarization at wavelengths ranging from 0.25 to $2.5\rm{\mu m}$, an effect that is found to increase with the jet luminosity. Thus, future photometric and polarimetric campaigns should observe kilonovae in blue and red filters for a few days after the merger to help constrain the properties of the ejecta (e.g. composition) and jet.
PubDate: Thu, 25 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1583
Issue No: Vol. 523, No. 2 (2023)
- Resolving ambiguities in the inferred star formation histories of intense
[O iii] emitters in the reionization Era-
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Pages: 3018 - 3024
Abstract: ABSTRACTEarly JWST spectroscopic campaigns have confirmed the presence of strong [O iii] line-emitting galaxies in the redshift interval 7 < z < 9. Although deduced earlier from Spitzer photometry as an indicative of young stellar populations, some studies suggested the relevant photometric excesses attributed to [O iii] emission could, in part, be due to Balmer breaks arising from older stars. We demonstrate that this is likely the case by exploiting medium-band near-infrared JWST photometry in the Hubble Ultra Deep Field. We locate a sample of six galaxies with redshifts 8.2<z <8.6 for which the relevant medium-band filters enables us to separate the contributions of [O iii] emission and a Balmer break, thereby breaking earlier degeneracies of interpretation. The technique is particularly valuable since it provides photometric redshifts whose precision, $\Delta \, z\simeq \, \pm 0.08$, approaches that of spectroscopic campaigns now underway with JWST. Although some sources are young, a third of our sample have prominent Balmer breaks consistent with stellar ages of ≥150 Myr. Our results indicate that even intense [O iii] emitters experienced episodes of earlier star formation to z ∼10 and beyond, as is now being independently deduced from direct detection of the progenitors of similar systems.
PubDate: Fri, 26 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1597
Issue No: Vol. 523, No. 2 (2023)
- Star-forming environments in smoothed particle magnetohydrodynamics
simulations I: clump extraction and properties-
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Pages: 3025 - 3042
Abstract: ABSTRACTWhat is the nature of a star-forming clump' Observations reveal these to be chaotic environments being modified and influenced by many physical processes. However, numerical simulations often define these initial star-forming clumps to be idealized objects. In this paper, we define and analyse 109 star-forming clumps extracted from our previous low-mass star cluster simulations. To define a clump, we identify all the gas in a simulation that ever becomes bound to or accreted onto a star, then follow the gas backwards in time until it decreases to a critical density. This gas and its neighbouring gas are defined as our star-forming clump. Our clumps span a mass range of 0.15 ≲ M/M⊙ ≲ 10.2, while the density range within each clump spans 2–4 orders of magnitude. The gas density distribution is not smooth, indicating that it is highly structured. The clumps are turbulent, with no coherent rotation. Independent of the initial magnetic field strength of the parent cloud, all clumps yield a similar range of field strengths. The clump magnetic field is ordered but not reflective of the initial field geometry of the parent cloud. In general, most clump properties have a slight trend with clump mass but are independent of (or only very weakly dependent on) the properties of the parent cloud. We conclude that stars are born from a wide variety of environments and there is not a single universal star-forming clump.
PubDate: Mon, 29 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1605
Issue No: Vol. 523, No. 2 (2023)
- Timing the X-ray pulsating companion of the hot subdwarf HD 49798
with NICER-
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Pages: 3043 - 3048
Abstract: ABSTRACTHD 49798 is a hot subdwarf of O spectral type in a 1.55 d orbit with the X-ray source RX J0648.0−4418, a compact object with a spin period of $13.2\,$s. We use recent data from the Neutron Star Interior Composition Explorer instrument, joined with archival data from XMM–Newton and ROSAT, to obtain a phase-connected timing solution spanning ∼30 yr. Contrary to previous works, which relied on parameters determined through optical observations, the new timing solution could be derived using only X-ray data. We confirm that the compact object is steadily spinning up with $\dot{P} = -2.28(2) \times 10^{-15}\,$s s−1 and obtain a refined measure of the projected semimajor axis of the compact object aXsin i = 9.60(5) light-second. This allows us to determine the inclination and masses of the system as $i=84.5(7)\,$deg, MX = 1.220(8) $\rm {M}_\odot$, and $M_{\rm opt}=1.41(2)\,$$\rm {M}_\odot$. We also study possible long-term (approximately years) and orbital variations of the soft X-ray pulsed flux, without finding evidence for variability. In the light of the new findings, we discuss the nature of the compact object, concluding that the possibility of a neutron star in the subsonic propeller regime is unlikely, while accretion of the subdwarf wind on to a massive white dwarf can explain the observed luminosity and spin-up rate for a wind velocity of ∼800 km s−1.
PubDate: Mon, 05 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1611
Issue No: Vol. 523, No. 2 (2023)
- Efficient radial migration by giant molecular clouds in the first several
hundred Myr after the stellar birth-
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Pages: 3049 - 3068
Abstract: ABSTRACTStars in the Galactic disc, including the Solar system, have deviated from their birth orbits and have experienced radial mixing and vertical heating. By performing hydrodynamical simulations of a galactic disc, we investigate how much tracer particles, which are initially located in the disc to mimic newborn stars and the thin and thick disc stars, are displaced from initial near-circular orbits by gravitational interactions with giant molecular clouds (GMCs). To exclude the influence of other perturbers that can change the stellar orbits, such as spiral arms and the bar, we use an axisymmetric form for the entire galactic potential. First, we investigate the time evolution of the radial and vertical velocity dispersion σR and σz by comparing them with a power-law relation of σ ∝ tβ. Although the exponents β decrease with time, they keep large values of 0.3 ∼ 0.6 for 1 Gyr, indicating fast and efficient disc heating. Next, we find that the efficient stellar scattering by GMCs also causes a change in angular momentum for each star and, therefore, radial migration. This effect is more pronounced in newborn stars than old disc stars; nearly 30 per cent of stars initially located on the galactic mid-plane move more than 1 kpc in the radial direction for 1 Gyr. The dynamical heating and radial migration drastically occur in the first several hundred Myr. As the amplitude of the vertical oscillation increases, the time spent in the galactic plane, where most GMCs are distributed, decreases, and the rate of an increase in the heating and migration slows down.
PubDate: Mon, 29 May 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1612
Issue No: Vol. 523, No. 2 (2023)
- Two warm Neptunes transiting HIP 9618 revealed by TESS and
Cheops-
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Pages: 3069 - 3089
Abstract: ABSTRACTHIP 9618 (HD 12572, TOI-1471, TIC 306263608) is a bright (G = 9.0 mag) solar analogue. TESS photometry revealed the star to have two candidate planets with radii of 3.9 ± 0.044 R⊕ (HIP 9618 b) and 3.343 ± 0.039 R⊕ (HIP 9618 c). While the 20.77291 d period of HIP 9618 b was measured unambiguously, HIP 9618 c showed only two transits separated by a 680-d gap in the time series, leaving many possibilities for the period. To solve this issue, CHEOPS performed targeted photometry of period aliases to attempt to recover the true period of planet c, and successfully determined the true period to be 52.56349 d. High-resolution spectroscopy with HARPS-N, SOPHIE, and CAFE revealed a mass of 10.0 ± 3.1M⊕ for HIP 9618 b, which, according to our interior structure models, corresponds to a $6.8\pm 1.4~{{\ \rm per\ cent}}$ gas fraction. HIP 9618 c appears to have a lower mass than HIP 9618 b, with a 3-sigma upper limit of <18M⊕. Follow-up and archival RV measurements also reveal a clear long-term trend which, when combined with imaging and astrometric information, reveal a low-mass companion ($0.08^{+0.12}_{-0.05} M_\odot$) orbiting at $26.0^{+19.0}_{-11.0}$ au. This detection makes HIP 9618 one of only five bright (K < 8 mag) transiting multiplanet systems known to host a planet with P > 50 d, opening the door for the atmospheric characterization of warm (Teq < 750 K) sub-Neptunes.
PubDate: Thu, 08 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1319
Issue No: Vol. 523, No. 2 (2023)
- TESS and CHEOPS discover two warm sub-Neptunes transiting the bright
K-dwarf HD 15906-
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Pages: 3090 - 3118
Abstract: ABSTRACTWe report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 ± 0.08 R⊕ and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93$^{+0.07}_{-0.06}$ R⊕ and a period of 21.583298$^{+0.000052}_{-0.000055}$ d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm (≲ 700 K) sub-Neptune sized planets transiting a bright star (G ≤ 10 mag). It is an excellent target for detailed characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.
PubDate: Thu, 08 Jun 2023 00:00:00 GMT
DOI: 10.1093/mnras/stad1369
Issue No: Vol. 523, No. 2 (2023)
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