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Monthly Notices of the Royal Astronomical Society
Journal Prestige (SJR): 2.346
Citation Impact (citeScore): 4
Number of Followers: 15  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0035-8711 - ISSN (Online) 1365-2966
Published by Oxford University Press Homepage  [425 journals]
  • 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)
       
  • 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

    • Free pre-print version: Loading...

      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

    • Free pre-print version: Loading...

      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

    • Free pre-print version: Loading...

      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

    • Free pre-print version: Loading...

      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

    • Free pre-print version: Loading...

      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

    • Free pre-print version: Loading...

      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)
       
 
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