Subjects -> ASTRONOMY (Total: 94 journals)
Showing 1 - 46 of 46 Journals sorted alphabetically
Advances in Astronomy     Open Access   (Followers: 49)
Annual Review of Astronomy and Astrophysics     Full-text available via subscription   (Followers: 50)
Annual Review of Earth and Planetary Sciences     Full-text available via subscription   (Followers: 67)
Artificial Satellites     Open Access   (Followers: 21)
Astrobiology     Hybrid Journal   (Followers: 11)
Astronomical & Astrophysical Transactions: The Journal of the Eurasian Astronomical Society     Hybrid Journal   (Followers: 7)
Astronomical Review     Open Access   (Followers: 5)
Astronomische Nachrichten     Hybrid Journal   (Followers: 4)
Astronomy & Geophysics     Hybrid Journal   (Followers: 49)
Astronomy and Astrophysics     Full-text available via subscription   (Followers: 67)
Astronomy and Computing     Hybrid Journal   (Followers: 6)
Astronomy Letters     Hybrid Journal   (Followers: 22)
Astronomy Reports     Hybrid Journal   (Followers: 22)
Astronomy Studies Development     Open Access   (Followers: 15)
Astroparticle Physics     Hybrid Journal   (Followers: 10)
Astrophysical Bulletin     Hybrid Journal   (Followers: 4)
Astrophysics     Hybrid Journal   (Followers: 35)
Astrophysics and Space Science     Hybrid Journal   (Followers: 49)
Astrophysics and Space Sciences Transactions (ASTRA)     Open Access   (Followers: 60)
Astropolitics: The International Journal of Space Politics & Policy     Hybrid Journal   (Followers: 13)
Celestial Mechanics and Dynamical Astronomy     Hybrid Journal   (Followers: 15)
Chinese Astronomy and Astrophysics     Full-text available via subscription   (Followers: 25)
Colloid Journal     Hybrid Journal   (Followers: 2)
Comptes Rendus : Physique     Open Access   (Followers: 2)
Computational Astrophysics and Cosmology     Open Access   (Followers: 6)
Earth and Planetary Science Letters     Hybrid Journal   (Followers: 143)
Earth, Moon, and Planets     Hybrid Journal   (Followers: 47)
Earth, Planets and Space     Open Access   (Followers: 77)
EAS Publications Series     Full-text available via subscription   (Followers: 8)
EPL Europhysics Letters     Partially Free   (Followers: 8)
Experimental Astronomy     Hybrid Journal   (Followers: 38)
Expert Opinion on Astronomy and Astrophysics     Open Access   (Followers: 8)
Extreme Life, Biospeology & Astrobiology - International Journal of the Bioflux Society     Full-text available via subscription   (Followers: 4)
Few-Body Systems     Hybrid Journal   (Followers: 1)
Foundations of Physics     Hybrid Journal   (Followers: 40)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 15)
Galaxies     Open Access   (Followers: 6)
Globe, The     Full-text available via subscription   (Followers: 3)
Gravitation and Cosmology     Hybrid Journal   (Followers: 6)
Icarus     Hybrid Journal   (Followers: 71)
International Journal of Advanced Astronomy     Open Access   (Followers: 21)
International Journal of Astrobiology     Hybrid Journal   (Followers: 4)
International Journal of Astronomy     Open Access   (Followers: 22)
International Journal of Astronomy and Astrophysics     Open Access   (Followers: 36)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 15)
International Letters of Chemistry, Physics and Astronomy     Open Access   (Followers: 8)
ISRN Astronomy and Astrophysics     Open Access   (Followers: 14)
Journal for the History of Astronomy     Full-text available via subscription   (Followers: 20)
Journal of Astrobiology & Outreach     Open Access   (Followers: 5)
Journal of Astronomical Instrumentation     Open Access   (Followers: 3)
Journal of Astrophysics     Open Access   (Followers: 33)
Journal of Astrophysics and Astronomy     Open Access   (Followers: 58)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 133)
Journal of Geophysical Research : Planets     Full-text available via subscription   (Followers: 116)
Journal of Geophysical Research : Space Physics     Full-text available via subscription   (Followers: 136)
Journal of High Energy Astrophysics     Full-text available via subscription   (Followers: 25)
Kinematics and Physics of Celestial Bodies     Hybrid Journal   (Followers: 11)
KronoScope     Hybrid Journal   (Followers: 1)
Macalester Journal of Physics and Astronomy     Open Access   (Followers: 5)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 13)
Monthly Notices of the Royal Astronomical Society : Letters     Hybrid Journal   (Followers: 2)
Nature Astronomy     Hybrid Journal   (Followers: 14)
New Astronomy     Hybrid Journal   (Followers: 26)
New Astronomy Reviews     Full-text available via subscription   (Followers: 19)
Nonlinear Dynamics     Hybrid Journal   (Followers: 19)
NRIAG Journal of Astronomy and Geophysics     Open Access   (Followers: 4)
Physics of the Dark Universe     Open Access   (Followers: 4)
Planetary and Space Science     Hybrid Journal   (Followers: 106)
Planetary Science     Open Access   (Followers: 52)
Proceedings of the International Astronomical Union     Full-text available via subscription   (Followers: 2)
Publications of the Astronomical Society of Australia     Hybrid Journal   (Followers: 3)
Publications of the Astronomical Society of Japan     Hybrid Journal   (Followers: 4)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 20)
Research in Astronomy and Astrophysics     Full-text available via subscription   (Followers: 38)
Revista Mexicana de Astronomía y Astrofísica     Open Access   (Followers: 3)
Science China : Physics, Mechanics & Astronomy     Full-text available via subscription   (Followers: 4)
Science China Physics, Mechanics & Astronomy     Hybrid Journal   (Followers: 4)
Solar Physics     Hybrid Journal   (Followers: 29)
Solar System Research     Hybrid Journal   (Followers: 15)
Space Science International     Open Access   (Followers: 118)
Space Science Reviews     Hybrid Journal   (Followers: 92)
Space Weather     Full-text available via subscription   (Followers: 27)
Transport and Aerospace Engineering     Open Access   (Followers: 13)
Universe     Open Access   (Followers: 6)
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Publications of the Astronomical Society of Japan
Journal Prestige (SJR): 0.877
Citation Impact (citeScore): 1
Number of Followers: 4  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0004-6264 - ISSN (Online) 2053-051X
Published by Oxford University Press Homepage  [419 journals]
  • Investigation of the upper atmosphere in ultra-hot Jupiter WASP-76 b with
           high-resolution spectroscopy

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      Authors: Kawauchi K; Narita N, Sato B, et al.
      Pages: 225 - 238
      Abstract: AbstractAlkali metal lines are one of the most important key opacity sources for understanding exoplanetary atmospheres because the Na i resonance doublets are thought to be the cause of low albedo, as the alkali metal’s wide line wings absorb almost all of the incoming stellar irradiation. High-resolution transmission spectroscopy of Na absorption lines can be used to investigate the temperature of the thermosphere of hot Jupiters, which is increased by stellar X-ray and extreme-ultraviolet irradiation. We applied high-resolution transmission spectroscopy to the ultra-hot Jupiter WASP-76 b with the High Dispersion Spectrograph (HDS) on the Subaru 8.2 m telescope. We report the detection of strong Na D excess absorption with line contrasts of $0.42 \pm 0.03\%$ (D1 at 5895.92 Å) and $0.38\pm 0.04\%$ (D2 at 5889.95 Å), full width at half maximum values of 1.63 ± 0.13 Å (D1) and 1.87 ± 0.22 Å (D2), and equivalent widths of (7.29 ± 1.43) × 10−3 Å (D1) and (7.56 ± 2.38) × 10−3 Å (D2). These results show that the Na D absorption lines are shallower and broader than those in previous work, whereas the absorption signals over the same passband are consistent with those in previous work. We derive the best-fitting isothermal temperature of 3700 K (without rotation) and 4200 K (with rotation). These results suggest the possibility of the existence of a thermosphere because the derived atmospheric temperature is higher than the equilibrium temperature (∼2160 K).
      PubDate: Thu, 27 Jan 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab120
      Issue No: Vol. 74, No. 2 (2022)
       
  • The radio dichotomy of active galactic nuclei

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      Authors: Xiao H; Zhu J, Fu L, et al.
      Pages: 239 - 246
      Abstract: AbstractThe question of radio dichotomy in active galactic nuclei (AGNs) is still in debate, even though it has been discussed for more than 40 years. In order to solve this old riddle, we collect a sample of AGNs with optical B band and radio 6 cm wavelength data to analyze the radio loudness log R. Our results indicate a separation of log R = 〈1.37 ± 0.02〉 between radio-loud (RL) AGNs and radio-quiet (RQ) AGNs, suggesting the existence of an RL/RQ dichotomy. For the first time, we suggest combining radio luminosity and radio loudness as a double criterion to divide AGNs into RLs and RQs to avoid misclassification problems that may happen in the single-criterion scenario; we propose the double-criterion dividing line log L6 cm = −2.7log R + 44.3 by using a machine-learning method. In addition, the key point of the RL/RQ dichotomy is the origin of radio emission for the two classes, and we suggest the radio emission from RLs and RQs share the same origin, e.g., jets and mini-jets (aborted-jet or outflow), through a correlation study between radio 6 cm luminosity and optical B-band luminosity.
      PubDate: Thu, 27 Jan 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab121
      Issue No: Vol. 74, No. 2 (2022)
       
  • Third data release of the Hyper Suprime-Cam Subaru Strategic Program

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      Authors: Aihara H; AlSayyad Y, Ando M, et al.
      Pages: 247 - 272
      Abstract: AbstractThis paper presents the third data release of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), a wide-field multi-band imaging survey with the Subaru 8.2 m telescope. HSC-SSP has three survey layers (Wide, Deep, and UltraDeep) with different area coverages and depths, designed to address a wide array of astrophysical questions. This third release from HSC-SSP includes data from 278 nights of observing time and covers about 670 deg2 in all five broad-band filters (grizy) at the full depth (∼26 mag at 5σ depending on filter) in the Wide layer. If we include partially observed areas, the release covers 1470 deg2. The Deep and UltraDeep layers have $\sim\! 80\%$ of the originally planned integration times, and are considered done, as we have slightly changed the observing strategy in order to compensate for various time losses. There are a number of updates in the image processing pipeline. Of particular importance is the change in the sky subtraction algorithm; we subtract the sky on small scales before the detection and measurement stages, which has significantly reduced the number of false detections. Thanks to this and other updates, the overall quality of the processed data has improved since the previous release. However, there are limitations in the data (for example, the pipeline is not optimized for crowded fields), and we encourage the user to check the quality assurance plots as well as a list of known issues before exploiting the data. The data release website is 〈https://hsc-release.mtk.nao.ac.jp〉.
      PubDate: Mon, 14 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab122
      Issue No: Vol. 74, No. 2 (2022)
       
  • Silicon and strontium abundances of very metal-poor stars determined from
           near-infrared spectra

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      Authors: Aoki W; Beers T, Honda S, et al.
      Pages: 273 - 282
      Abstract: AbstractSilicon and strontium are key elements to explore the nucleosynthesis and chemical evolution of the Galaxy by measurements of very metal-poor stars. There are, however, only a few useful spectral lines of these elements in the optical range that are measurable for such low-metallicity stars. Here we report on abundances of these two elements determined from near-infrared high-resolution spectra obtained with the Subaru Telescope Infrared Doppler instrument. Si abundances are determined for as many as 26 Si lines for six very and extremely metal-poor stars (−4.0 < [Fe/H] < −1.5), which significantly improves the reliability of the abundance measurements. All six stars, including three carbon-enhanced objects, show over-abundances of Si ([Si/Fe] ∼ +0.5). Two stars with [Fe/H] ∼ −1.5 have relatively small over-abundances. The [Mg/Si] ratios agree with the solar value, except for one metal-poor star with carbon excess. Strontium abundances are determined from the triplet lines for four stars, including two for the first time. The consistency of the Sr abundances determined from near-infrared and optical spectra require further examination from additional observations.
      PubDate: Wed, 02 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab123
      Issue No: Vol. 74, No. 2 (2022)
       
  • Deep near-infrared imaging observation of the faint X-ray point sources
           constituting the Galactic bulge X-ray emission

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      Authors: Morihana K; Tsujimoto M, Ebisawa K, et al.
      Pages: 283 - 297
      Abstract: AbstractThe presence of the apparently extended hard (2–10 keV) X-ray emission along the Galactic plane has been known since the early 1980s. With a deep X-ray exposure using the Chandra X-ray Observatory of a slightly off-plane region in the Galactic bulge, most of the extended emission was resolved into faint discrete X-ray sources in the Fe K band (Revnivtsev et al. 2009, Nature, 458, 1142). The major constituents of these sources have long been considered to be X-ray active stars and magnetic cataclysmic variables (CVs). However, recent works including our near-infrared (NIR) imaging and spectroscopic studies (Morihana et al. 2013, ApJ, 766, 14; Morihana et al. 2016, PASJ, 68, 57) argue that other populations should be more dominant. To investigate this further, we conducted a much deeper NIR imaging observation at the center of the Chandra’s exposure field. We have used the MOIRCS on the Subaru telescope, reaching the limiting magnitude of ∼18 mag in the J, H, and Ks bands in this crowded region, and identified ${\sim}50\%$ of the X-ray sources with NIR candidate counterparts. We classified the X-ray sources into three groups (A, B, and C) based on their positions in the X-ray color–color diagram and characterized them based on the X-ray and NIR features. We argue that the major populations of the Group A and C sources are, respectively, CVs (binaries containing magnetic or non-magnetic white dwarfs with high accretion rates) and X-ray active stars. The major population of the Group B sources is presumably white dwarf (WD) binaries with low mass accretion rates. The Fe K equivalent width in the composite X-ray spectrum of the Group B sources is the largest among the three and comparable to that of the Galactic bulge X-ray emission. This leads us to speculate that there are numerous WD binaries with low mass accretion rates which are not recognized as CVs but are the major contributor of the apparently extended X-ray emission.
      PubDate: Mon, 07 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab124
      Issue No: Vol. 74, No. 2 (2022)
       
  • Abundances of phosphorus in bright F-G type main-sequence stars

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      Authors: Sadakane K; Nishimura M.
      Pages: 298 - 307
      Abstract: AbstractAbundances of phosphorus (P) in 45 main sequence F-G type stars (including the Sun by using reflected light from the minor planet Vesta) in the metallicity range [Fe/H] from −0.4 to +0.3 have been determined. The effective temperatures of target stars range from 5500 to 6600 K. Two lines of P i at 9750.75 Å and at 9796.83 Å (multiplet No. 2) are analysed by using a profile fitting method. Significant star-to-star scatters up to 0.4 dex have been found at all metallicities. We find three stars (HD 9826, HD 20010, and HD 82328) in which values of [P/Fe] are lower than −0.20, showing that P is deficient with respect to Fe in these stars. Such objects have never been reported in the past and may have an impact on the theoretical studies of origin and evolution of P. The sample contains 18 stars with confirmed planets (not including the Sun) and no significant difference in abundance of P has been found between stars with planets and those with no confirmed planet.
      PubDate: Wed, 16 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab125
      Issue No: Vol. 74, No. 2 (2022)
       
  • Modeling of 3D trajectory of Hayabusa2 re-entry based on acoustic
           observations

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      Authors: Nishikawa Y; Yamamoto M, Sansom E, et al.
      Pages: 308 - 317
      Abstract: AbstractOn 2020 December 5 at 17:28 UTC, Japan Aerospace Exploration Agency’s Hayabusa2 sample return capsule (SRC) re-entered Earth’s atmosphere. The capsule passed through the atmosphere at supersonic speeds, emitting sound and light. The inaudible sound was recorded by infrasound sensors installed by Kochi University of Technology and Curtin University. Based on analysis of the recorded infrasound, the trajectory of the SRC in two cases, one with constant-velocity linear motion and the other with silent flight, could be estimated with an accuracy of ${0{_{.}^{\circ}}5}$ in elevation and 1° in direction. A comparison with optical observations suggests a state of flight in which no light is emitted but sound is emitted. In this paper, we describe the method and results of the trajectory estimation.
      PubDate: Sat, 12 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab126
      Issue No: Vol. 74, No. 2 (2022)
       
  • Hα emission in the outskirts of galaxies at z = 0.4

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      Authors: Shimakawa R; Tanaka M, Kikuta S, et al.
      Pages: 318 - 325
      Abstract: AbstractThis paper reports detections of Hα emission and stellar continuum out to approximately 30 physical kiloparsecs, and Hα directionality in the outskirts of Hα-emitting galaxies (Hα emitters) at $z$ = 0.4. This research adopts narrow-band selected Hα emitters at $z$ = 0.4 from the emission-line object catalog by Hayashi et al. (2020, PASJ, 72, 86), which is based on data in the Deep and Ultradeep layers of the Hyper Suprime-Cam Subaru Strategic Program. Deep narrow- and broad-band images of 8625 Hα emitters across 16.8 deg2 enable us to construct deep composite emission-line and continuum images. The stacked images show diffuse Hα emission (down to ∼5 × 10−20 erg s−1 cm−2 arcsec−2) and stellar continuum (down to ∼5 × 10−22 erg s−1 cm−2 Å−1 arcsec−2), extending beyond 10 kpc at stellar masses >109 $M_\odot$, parts of which may originate from stellar halos. Those radial profiles are broadly consistent with each other. In addition, we obtain a dependence of the Hα emission on the position angle because relatively higher Hα equivalent width has been detected along the minor-axis towards galaxy disks. While the Hα directionality could be attributed to biconical outflows, further research with hydrodynamic simulations is highly demanded to pin down the exact cause.
      PubDate: Mon, 14 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab127
      Issue No: Vol. 74, No. 2 (2022)
       
  • Red dwarf contact binary V0627 Hydrae

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      Authors: Xu H; Zhu L, Thawicharat S, et al.
      Pages: 326 - 333
      Abstract: AbstractNew complete light curves in B, V, RC, and IC bands for the short-period eclipsing binary V0627 Hya (period shorter than 0.22 d) are presented. From the longer wavelength to the shorter one, the amplitudes of the light variation become larger. The different height of the successive maxima in each band’s light curve could be seen clearly. We analyzed those multi-wavelength light curves using the Wilson–Devinney code and derived the photometric solutions of V0627 Hya for the first time. It is found that V0627 Hya is a W-type shallow-contact binary. Combined with the GAIA parallax, the absolute parameters of this system are obtained: M1 = 0.31 M⊙, M2 = 0.64 M⊙, R1 = 0.50 R⊙, R2 = 0.69 R⊙, L1 = 0.06 L⊙, L2 = 0.08 L⊙. Thus, V0627 Hya is a new member of the red dwarf contact binary class. The asymmetry in the light curves could be explained by the spot model due to the magnetic activity of its late-type component. The amplitude differences in the different bands’ light curves imply the existence of a cool third body, which is supported by the third light contribution in the photometric solutions. The third body in this system may play an important role in its formation and evolution by removing the angular momentum. More red dwarf contact binaries need to be found and studied, since they are rare and not enough is known to reveal their mysteries at present.
      PubDate: Thu, 17 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab128
      Issue No: Vol. 74, No. 2 (2022)
       
  • Discovery of stable titanium at the northeastern jet of Cassiopeia A: Need
           for a weak jet mechanism'

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      Authors: Ikeda T; Uchiyama Y, Sato T, et al.
      Pages: 334 - 342
      Abstract: AbstractThe origin of the jet-like structures observed in Cassiopeia A is still unclear, although it seems to be related to its explosion mechanism. X-ray observations of the characteristic structures could provide us useful information on the explosive nucleosynthesis via the observation of elements, which is a unique approach to understand its origin. We here report the discovery of shocked stable Ti, which is produced only at the inner region of exploding stars, in the northeast jet of Cassiopeia A using the 1 Ms deep observation with the Chandra X-ray observatory. The observed Ti coexists with other intermediate-mass elements (e.g., Si, S, Ar, Ca) and Fe at the tip of the X-ray jet structure. We found that its elemental composition is explained well with the production by the incomplete Si burning regime, indicating that the formation process of the jet structure was sub-energetic at the explosion (the peak temperature during the nuclear burning must be ≲5 × 109 K at most). Thus, we conclude that the energy source that formed the jet structure was not the primary engine for the supernova explosion. Our results are useful to limit the power of the jet-structure formation process, and a weak jet mechanism with low temperature may be needed to explain it.
      PubDate: Wed, 16 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab130
      Issue No: Vol. 74, No. 2 (2022)
       
  • Properties of molecular gas in galaxies in early and mid stages of
           Interaction. III. Resolved Kennicutt–Schmidt law

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      Authors: Kaneko H; Kuno N, Iono D, et al.
      Pages: 343 - 363
      Abstract: AbstractWe study properties of the interstellar medium, an ingredient of stars, and star formation activity, in four nearby galaxy pairs in the early and mid stages of interaction for both a galaxy scale and a kpc scale. The galaxy-scale Kennicutt–Schmidt law shows that seven of eight interacting galaxies have a star formation rate within a factor of three compared with the best fit of the isolated galaxies, although we have shown that molecular hydrogen gas is efficiently produced from atomic hydrogen during the interaction in the previous paper (Kaneko et al. 2017 PASJ, 69, 66). The galaxy-scale specific star formation rate (sSFR) and star formation efficiency (SFE) in interacting galaxies are comparable to those in isolated galaxies. We also investigate SFE and the Kennicutt–Schmidt law on a kpc scale. The spatial distributions of SFE reveal that SFE is locally enhanced, and the enhanced regions take place asymmetrically or at off-centre regions. The local enhancement of SFE could be induced by shock. We find that the index of the Kennicutt–Schmidt law for the interacting galaxies in the early stage is 1.30 ± 0.04, which is consistent with that of the isolated galaxies. Since CO emission, which is used in the Kennicutt–Schmidt law, is a tracer of the amount of molecular gas, this fact suggests that dense gas, which is more directly connected to star formation, is not changed at the early stage of interaction.
      PubDate: Tue, 22 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab129
      Issue No: Vol. 74, No. 2 (2022)
       
  • Simulation-based spectral analysis of X-ray CCD data affected by photon
           pile-up

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      Authors: Tamba T; Odaka H, Bamba A, et al.
      Pages: 364 - 383
      Abstract: AbstractWe have developed a simulation-based method of spectral analysis for pile-up-affected data of X-ray CCDs without any loss of photon statistics. As effects of the photon pile-up appear as complicated nonlinear detector responses, we employ a detailed simulation to calculate the important processes in an X-ray observation including physical interactions, detector signal generation, detector readout, and a series of data reduction processes. This simulation naturally reproduces X-ray-like and background-like events as results of X-ray photon merging in a single pixel or in a chunk of adjacent pixels, allowing us to construct a nonlinear spectral analysis framework that can treat pile-up-affected observation data. For validation, we have performed data analysis of Suzaku X-ray Imaging Spectrometer (XIS) observations using this framework with various parameters of the detector simulation, all of which are optimized for that instrument. We present three cases of different pile-up degrees: PKS 2155−304 (negligible pile-up), Aquila X-1 (moderate pile-up), and the Crab Nebula (strong pile-up); we show that the nonlinear analysis method produces results consistent with a conventional linear analysis for the negligible pile-up condition, and accurately corrects well-known pile-up effects such as spectral hardening and flux decrease for the pile-up cases. These corrected results are consistent with those obtained by a widely used core-exclusion method or by other observatories with much higher timing resolutions (without pile-up). Our framework is applicable to any types of CCDs used for X-ray astronomy, including future missions such as X-ray Imaging and Spectroscopy Mission (XRISM), by appropriate optimization of the simulation parameters.
      PubDate: Mon, 07 Mar 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab131
      Issue No: Vol. 74, No. 2 (2022)
       
  • Structure of the super-Eddington outflow and its impact on the
           cosmological scale

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      Authors: Botella I; Mineshige S, Kitaki T, et al.
      Pages: 384 - 397
      Abstract: AbstractIt is one of the biggest issues in black hole (BH) astrophysics how to evaluate BH feedback to its environments precisely. Aiming at studying the unique gas dynamics of super-Eddington flow around supermassive black hole (SMBH) seeds at high redshift, we carried out axisymmetric two-dimensional radiation hydrodynamic simulations using a nested simulation-box method. Here we divide the simulation box into an inner zone at (2–3 × 103)rSch (with rSch being the Schwarzschild radius) and an outer zone at (2 × 103–3 × 106)rSch, with smooth connection of the physical quantities, such as gas density, velocity, and radiation energy. We start the calculation by injecting mass through the outer boundary of the inner zone at a constant rate of $\dot{M}_{\rm {inj}}=10^3L_{\rm {Edd}}/c^2$, where LEdd is the Eddington luminosity and c is the speed of light. A powerful outflow is generated in the innermost region and it propagates from the inner zone to the outer zone. The outflows are characterized by a velocity of 0.02c (0.7c) and density of 10−17 (10−19) g cm−3 for near the edge-on (face-on) direction. The outflow is gradually accelerated as it travels by accepting radiation-pressure force. The final mass outflow rate at the outermost boundary is $\dot{M}_{\rm {out}}\sim 0.3 \times \dot{M}_{\rm {inj}}$. By extrapolating the outflow structure to a further larger scale, we find that the momentum and energy fluxes at r ∼ 0.1 pc are ∼10–100 LEdd/c and ∼0.1–10 LEdd, respectively. Moreover, we find that the impacts are highly anisotropic, in the sense that larger impacts occur towards the face-on direction than in the edge-on direction. These results indicate that the BH feedback will work more efficiently on the interstellar medium than assumed in the cosmological simulations.
      PubDate: Thu, 24 Feb 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psac001
      Issue No: Vol. 74, No. 2 (2022)
       
  • Do blue galaxy-clusters have hot intracluster gas'

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      Authors: Misato R; Toba Y, Ota N, et al.
      Pages: 398 - 406
      Abstract: AbstractWe present herein a systematic X-ray analysis of blue galaxy clusters at z = 0.84 discovered by the Subaru telescope. The sample consisted of 43 clusters identified by combining red-sequence and blue-cloud surveys, covering a wide range of emitter fractions (i.e., 0.3–0.8). The spatial extent of the over-density region of emitter galaxies was approximately 1 Mpc in radius. The average cluster mass was estimated as 0.6(<1.5) × 1014 M⊙ from the stacked weak-lensing measurement. We analyzed the XMM-Newton archival data, and measured the X-ray luminosity of the hot intracluster medium. As a result, diffuse X-ray emission was marginally detected in 14 clusters, yielding an average luminosity of 5 × 1042 erg s−1. To the contrary, it was not significant in 29 clusters. The blue clusters were significantly fainter than the red-dominated clusters, and the X-ray luminosity did not show any meaningful correlation either with emitter fraction or richness. The X-ray surface brightness was low, but the amount of gas mass was estimated to be comparable to that observed in the 1013–1014 M⊙ cluster. Based on the results, we suggest that the blue clusters are at the early formation stage, and the gas is yet to be compressed and heated up to produce appreciable X-rays. Follow-up spectroscopic measurements are essential to clarify the dynamical status and co-evolution of galaxies and hot gas in the blue clusters.
      PubDate: Wed, 02 Mar 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psac002
      Issue No: Vol. 74, No. 2 (2022)
       
  • Spatially-resolved relation between [C i] 3P1–3P0 and 12CO (1–0) in
           Arp 220

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      Authors: Ueda J; Michiyama T, Iono D, et al.
      Pages: 407 - 420
      Abstract: AbstractWe present $\sim {0.^{\prime \prime }3}$ (114 pc) resolution maps of [C i] 3P1–3P0 (hereafter [C i] (1–0)) and 12CO (1–0) obtained toward Arp 220 with the Atacama Large Millimeter/submillimeter Array. The overall distribution of the [C i] (1–0) emission is consistent with the CO (1–0). While the [C i] (1–0) and CO (1–0) luminosities of the system follow the empirical linear relation for the unresolved ULIRG sample, we find a sublinear relation between [C i] (1–0) and CO (1–0) using the spatially-resolved data. We measure the [C i] (1–0)$/$CO (1–0) luminosity ratio per pixel in star-forming environments of Arp 220 and investigate its dependence on the CO (3–2)$/$CO (1–0) ratio (RCO). On average, the [C i] (1–0)$/$CO (1–0) luminosity ratio is almost constant up to RCO ≃ 1 and then increases with RCO. According to the radiative transfer analysis, a high C i$/$CO abundance ratio is required in regions with high [C i] (1–0)$/$CO (1–0) luminosity ratios and RCO > 1, suggesting that the C i$/$CO abundance ratio varies at ∼100 pc scale in Arp 220. The [C i] (1–0)$/$CO (1–0) luminosity ratio depends on multiple factors and may not be straightforward to interpret. We also find the high-velocity components traced by [C i] (1–0) in the western nucleus, likely associated with the molecular outflow. The [C i] (1–0)$/$CO (1–0) luminosity ratio in the putative outflow is 0.87 ± 0.28, which is four times higher than the average ratio of Arp 220. While there is a possibility that the [C i] (1–0) and CO (1–0) emission traces different components, we suggest that the high line ratios are likely to be because of elevated C i$/$CO abundance ratios based on our radiative transfer analysis. A C i-rich and CO-poor gas phase in outflows could be caused by the irradiation of the cosmic rays, the shock heating, and the intense radiation field.
      PubDate: Wed, 16 Mar 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psac004
      Issue No: Vol. 74, No. 2 (2022)
       
  • The three-year shear catalog of the Subaru Hyper Suprime-Cam SSP Survey

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      Authors: Li X; Miyatake H, Luo W, et al.
      Pages: 421 - 459
      Abstract: AbstractWe present the galaxy shear catalog that will be used for the three-year cosmological weak gravitational lensing analyses using data from the Wide layer of the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) Survey. The galaxy shapes are measured from the i-band imaging data acquired from 2014 to 2019 and calibrated with image simulations that resemble the observing conditions of the survey based on training galaxy images from the Hubble Space Telescope in the COSMOS region. The catalog covers an area of 433.48 deg2 of the northern sky, split into six fields. The mean i-band seeing is ${0{^{\prime \prime}_{.}}59}$. With conservative galaxy selection criteria (e.g., i-band magnitude brighter than 24.5), the observed raw galaxy number density is 22.9 arcmin−2, and the effective galaxy number density is 19.9 arcmin−2. The calibration removes the galaxy property-dependent shear estimation bias to the level δm < 9 × 10−3. The bias residual δm shows no dependence on redshift in the range 0 < z ≤ 3. We define the requirements for cosmological weak-lensing science for this shear catalog, and quantify potential systematics in the catalog using a series of internal null tests for systematics related to point-spread function modelling and shear estimation. A variety of the null tests are statistically consistent with zero or within requirements, but (i) there is evidence for PSF model shape residual correlations; and (ii) star–galaxy shape correlations reveal additive systematics. Both effects become significant on >1° scales and will require mitigation during the inference of cosmological parameters using cosmic shear measurements.
      PubDate: Fri, 11 Mar 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psac006
      Issue No: Vol. 74, No. 2 (2022)
       
  • Spectroscopic observations of V455 Andromedae superoutburst in 2007: The
           most exotic spectral features in dwarf nova outbursts

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      Authors: Tampo Y; Nogami D, Kato T, et al.
      Pages: 460 - 476
      Abstract: AbstractWe present our spectroscopic observations of V455 Andromedae during the 2007 superoutburst. Our observations cover this superoutburst from around the optical peak of the outburst to the post-superoutburst stage. During the early superhump phase, the emission lines of the Balmer series, He i, He ii, Bowen blend, and C iv/N iv blend were detected. The He ii 4686 line exhibited a double-peaked emission profile, where Balmer emission lines were single-peaked, which is unexpected from its high inclination. In the ordinary superhump phase, the Balmer series transitioned to double-peaked emission profiles, and high-ionization lines were significantly weakened. These transitions of the line profiles should be related to the structural transformation of the accretion disk, as expected between the early and ordinary superhump transition in the thermal–tidal instability model. The Doppler map of Hα during the early superhump phase exhibits a compact blob centered at the primary white dwarf. In analogy to SW Sex-type cataclysmic variables, this feature could emerge from the disk wind and/or the mass accretion column on to the magnetized white dwarf. The Doppler map of He ii 4686 Å is dominated by the ring-like structure and imposed two flaring regions with the velocity of ∼300 km s−1, which is too slow for a Keplerian accretion disk. The phase of the flaring regions was coincident with the inner spiral arm structure identified during the early superhump phase. Our disk wind model with the enhanced emission from the wind component launched from the inner arm structure successfully reproduced the observed properties of He ii 4686 Å. Therefore, V455 And is the first case in dwarf nova outbursts where the presence of the disk wind is inferred from an optical spectrum.
      PubDate: Mon, 21 Mar 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psac007
      Issue No: Vol. 74, No. 2 (2022)
       
  • X-ray/Hα scaling relationships in stellar flares

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      Authors: Kawai H; Tsuboi Y, Iwakiri W, et al.
      Pages: 477 - 487
      Abstract: AbstractWe report on the results of our simultaneous observations of three large stellar flares with soft X-rays (SXRs) and an Hα emission line from two binary systems of RS CVn type. The energies released in the X-ray and Hα emissions during the flares were 1036–1038 and 1035–1037 erg, respectively. This renders the set of the observations as the first successful simultaneous X-ray/Hα observations of the stellar flares with energies above 1035 erg; although the coverage of the Hα observations was limited, with $\sim\! 10\%$ of the e-folding time in the decay phase of the flares, that of the SXR ones was complete. Combining the obtained physical parameters and those in literature for solar and stellar flares, we obtained a good proportional relation between the emitted energies of X-ray and Hα emissions for a flare energy range of 1029–1038 erg. The ratio of the Hα-line to bolometric X-ray emissions was ∼0.1, where the latter was estimated by converting the observed SXR emission to that in the 0.1–100 keV band according to the best-fitting thin thermal model. We also found that the e-folding times of the SXR and Hα light curves in the decaying phase of a flare are in agreement for a time range of 1–104 s. Even very large stellar flares with energies of six orders of magnitude larger than the most energetic solar flares follow the same scaling relationships with solar and much less energetic stellar flares. This fact suggests that their physical parameters can be estimated on the basis of the known physics of solar and stellar flares.
      PubDate: Mon, 21 Mar 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psac008
      Issue No: Vol. 74, No. 2 (2022)
       
  • Erratum: Cosmological constraints from cosmic shear two-point correlation
           functions with HSC survey first-year data

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      Authors: Hamana T; Shirasaki M, Miyazaki S, et al.
      Pages: 488 - 491
      Abstract: errata, addendacosmology: observationscosmological parametersdark matterlarge-scale structure of universe
      PubDate: Mon, 24 Jan 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psab117
      Issue No: Vol. 74, No. 2 (2022)
       
  • Corrigendum: Detailed analysis of the poorly studied northern open cluster
           NGC 1348 using multi-color photometry and GAIA EDR3 astrometry

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      Authors: Bisht D; Zhu Q, Elsanhoury W, et al.
      Pages: 492 - 492
      PubDate: Sat, 29 Jan 2022 00:00:00 GMT
      DOI: 10.1093/pasj/psac005
      Issue No: Vol. 74, No. 2 (2022)
       
 
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