Astronomy & Astrophysics最新文献

{"title":"4XMM J181330.1−175110: A new supergiant fast X-ray transient","authors":"M. Marelli, L. Sidoli, M. Polletta, A. De Luca, R. Salvaterra, A. Gargiulo","doi":"10.1051/0004-6361/202553768","DOIUrl":"https://doi.org/10.1051/0004-6361/202553768","url":null,"abstract":"<i>Context.<i/> Supergiant fast X-ray transients (SFXTs) are a subclass of high-mass X-ray binaries (HMXBs) in which a compact object accretes part of the clumpy wind of the blue supergiant companion, triggering series of brief X-ray flares lasting a few kiloseconds. Currently, only about 15 SFXTs are known.<i>Aims.<i/> The EXTraS (Exploring the X-ray Transient and variable Sky) catalog provides the timing signatures of every source observed by the EPIC instrument onboard <i>XMM-Newton<i/>. Among the most peculiar sources in terms of variability, we identified a new member of the SFXT family: 4XMM J181330.1−175110 (J1813).<i>Methods.<i/> We analyzed all publicly available <i>XMM-Newton<i/>, <i>Chandra<i/>, <i>Swift<i/>, and <i>NuSTAR<i/> data pointed at the J1813 position to determine the source’s duty cycle and to provide a comprehensive description of its timing and spectral behavior during its active phase. Additionally, we searched for the optical and infrared counterpart of the X-ray source in public databases and fitted its spectral energy distribution (SED).<i>Results.<i/> The optical-to-mid infrared SED of J1813 is consistent with a highly absorbed (<i>A<i/><sub><i>V<i/><sub/> ∼ 38) B0 star at ∼10 kpc. During its X-ray active phase, the source is characterized by continuous thousands seconds-long flares with peak luminosities (2–12 keV) ranging from 10<sup>34<sup/> to 4 × 10<sup>35<sup/> erg s<sup>−1<sup/>. Its X-ray spectrum is consistent with a high-absorbed power-law model with <i>N<i/><sub>H<sub/> ∼ 1.8 × 10<sup>23<sup/> cm<sup>−2<sup/> and Γ ∼ 1.66. No spectral variability was observed as a function of time or flux. J1813 is in a quiescent state ∼60% of the time, with an upper-limit luminosity of 8 × 10<sup>32<sup/> erg s<sup>−1<sup/> (at 10 kpc), implying an observed long-term X-ray flux variability > 500.<i>Conclusions.<i/> The optical counterpart alone indicates J1813 is an HMXB. Its transient nature, duty cycle, the amplitude of observed X-ray variability, the shape and luminosity of the X-ray flares – and the lack of known X-ray outbursts (> 10<sup>36<sup/> erg s<sup>−1<sup/>) – strongly support the identification of J1813 as an SFXT.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First snapshot of a magnetosphere around a Herbig Ae/Be star","authors":"S. P. Järvinen, S. Hubrig, M. Küker, U. Ziegler, I. Ilyin, M. Schöller, H. Adigozalzade, N. Ismailov, U. Bashirova","doi":"10.1051/0004-6361/202452980","DOIUrl":"https://doi.org/10.1051/0004-6361/202452980","url":null,"abstract":"<i>Context.<i/> The Herbig Ae/Be star HD 190073 is one of the very few magnetic Herbig Ae/Be stars for which close low-mass companions have been reported. Previously published magnetic field measurements indicated an annual change in the field configuration.<i>Aims.<i/> We aim to study in detail the spectral and magnetic variability of this star and characterise its magnetosphere for the first time.<i>Methods.<i/> Newly acquired and archival spectropolarimetric observations are combined to determine a more precise magnetic period and to constrain the geometry of the magnetic field. The variability of hydrogen line profiles is studied using dynamical spectra. Archival X-shooter observations of the He I 10 830 Å triplet are used to characterise its variability over the rotation cycle. Further, we carry out 2D magnetohydrodynamical (MHD) simulations of the magnetosphere using the NIRVANA MHD code.<i>Results.<i/> From the spectropolarimetric observations, we determine for HD 190073 a magnetic period <i>P<i/> = 51.70 ± 0.06 d. We estimate a magnetic obliquity angle <i>β<i/> = 82.9 ± 6.4° and a dipole strength <i>B<i/><sub>d<sub/> = 222 ± 66 G. Our dynamical spectra constructed for the hydrogen line profiles observed during 2011 clearly reveal a ringlike magnetospheric structure appearing at the rotation phase of best visibility of the positive magnetic pole. These spectra present the first snapshot of a magnetosphere around a Herbig Ae/Be star. 2D MHD simulations involving nonisothermal gas show that the magnetosphere is compact, with a radius of about 3 <i>R<i/><sub>*<sub/>, and that the wind flow extends over tens of <i>R<i/><sub>*<sub/>. With a reported radius of the accretion disk of 1.14 au around HD 190073, the distance between the star and the disk is about 25 <i>R<i/><sub>*<sub/>. The detection of a magnetosphere around HD 190073, and the possible presence of lower-mass companions at different distances, make this system a valuable laboratory for studying the magnetic interaction between the host star, its companions, and the accretion disk.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"64 7 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ALeRCE light curve classifier: Tidal disruption event expansion pack","authors":"M. Pavez-Herrera, P. Sánchez-Sáez, L. Hernández-García, F. E. Bauer, F. Förster, M. Catelan, A. Muñoz Arancibia, C. Ricci, I. Reyes-Jainaga, A. Bayo, P. Huijse, G. Cabrera-Vives","doi":"10.1051/0004-6361/202451951","DOIUrl":"https://doi.org/10.1051/0004-6361/202451951","url":null,"abstract":"<i>Context.<i/> ALeRCE (Automatic Learning for the Rapid Classification of Events) is currently processing the Zwicky Transient Facility (ZTF) alert stream, in preparation for the Vera C. Rubin Observatory, and classifying objects using a broad taxonomy. The ALeRCE light curve classifier is a balanced random forest (BRF) algorithm with a two-level scheme that uses variability features computed from the ZTF alert stream, and colors obtained from AllWISE and ZTF photometry.<i>Aims.<i/> This work develops an updated version of the ALeRCE broker light curve classifier that includes tidal disruption events (TDEs) as a new subclass. For this purpose we incorporated 24 new features, notably including the distance to the nearest source detected in ZTF science images and a parametric model of the power-law decay for transients. We also expanded the labeled set to include 219 792 spectroscopically classified sources, including 60 TDEs.<i>Methods.<i/> To effectively integrate TDEs into the ALeRCE’s taxonomy, we identified specific characteristics that set them apart from other transient classes, such as their central position in a galaxy, the typical decay pattern displayed when fully disrupted, and the lack of color variability after disruption. Based on these attributes, we developed features to distinguish TDEs from other transient events.<i>Results.<i/> The modified classifier can distinguish between a broad range of classes with a better performance compared to the previous version and it can integate the TDE class achieving 91% recall, also identifying a large number of potential TDE candidates in ZTF alert stream unlabeled data.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"5 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CAPOS: The bulge Cluster APOgee Survey","authors":"Lady Henao, Sandro Villanova, Doug Geisler, José G. Fernández-Trincado","doi":"10.1051/0004-6361/202451793","DOIUrl":"https://doi.org/10.1051/0004-6361/202451793","url":null,"abstract":"We performed a detailed abundance analysis of ten red giant members of the heavily obscured bulge globular cluster HP 1 using high-resolution, high S/N, near-infrared spectra collected with the Apache Point Observatory Galactic Evolution Experiment II survey (APOGEE-2), obtained as part of the bulge Cluster APOgee Survey (CAPOS). We investigated the chemical abundances for a variety of species, including the light (C, N), odd-Z (Al), <i>α<i/> (O, Mg, Si, S, Ca, and Ti), Fe-peak (Ni, Fe), and neutron-capture (Ce) elements. The derived mean cluster metallicity is [Fe/H] = −1.15 ± 0.03, with no evidence of an intrinsic metallicity spread. HP 1 exhibits a typical <i>α<i/> enrichment that follows the trend for similar metallicity Galactic globular clusters (GCs), such as NGC 288 and NGC 5904, although our [Si/Fe] abundances are relatively high. We find a significant nitrogen spread (~1 dex) and a large fraction of nitrogen-enhanced ([N/Fe] > +0.7) stars that populate the cluster. We also detect intrinsic star-to-star spreads in [C/Fe], [O/Fe], [Al/Fe], and [Ca/Fe], which are (anti)correlated with several chemical species, indicating the prevalence of the multiple-population phenomenon in HP 1. We uncover for the first time a possible correlation between Ca and Al, although the sample is small. The mean ⟨[Mg/Fe]⟩ = +0.29 and ⟨[Al/Fe]⟩ = +0.46 place HP 1 in the region dominated by in situ GCs, supporting the in situ nature of this cluster.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"17 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation-magnetohydrodynamics with MPI-AMRVAC using flux-limited diffusion","authors":"N. Narechania, R. Keppens, A. ud-Doula, N. Moens, J. Sundqvist","doi":"10.1051/0004-6361/202452208","DOIUrl":"https://doi.org/10.1051/0004-6361/202452208","url":null,"abstract":"<i>Context.<i/> Radiation plays a significant role in solar and astrophysical environments, as it may constitute a sizable fraction of the energy density, momentum flux, and total pressure. Modeling the dynamic interaction between radiation and magnetized plasmas in such environments is an intricate and computationally costly task.<i>Aims.<i/> The goal of this work is to demonstrate the capabilities of the open-source parallel, block-adaptive computational framework MPI-AMRVAC in solving equations of radiation-magnetohydrodynamics (RMHD) and to present benchmark test cases relevant for radiation-dominated magnetized plasmas.<i>Methods.<i/> We combined the existing magnetohydrodynamics (MHD) and flux-limited diffusion (FLD) radiative-hydrodynamics physics modules to solve the equations of RMHD on block-adaptive finite volume Cartesian meshes in any dimensionality.<i>Results.<i/> We introduce and validate several benchmark test cases, such as steady radiative MHD shocks, radiation-damped linear MHD waves, radiation-modified Riemann problems, and a multi-dimensional radiative magnetoconvection case. We recall the basic governing Rankine-Hugoniot relations for shocks and the dispersion relation for linear MHD waves in the presence of optically thick radiation fields where the diffusion limit is reached. The RMHD system allows for eight linear wave types, where the classical seven-wave MHD picture (entropy and three wave pairs for slow, Alfvén and fast) is augmented with a radiative diffusion mode.<i>Conclusions.<i/> The MPI-AMRVAC code now has the capability to perform multidimensional RMHD simulations with mesh adaptation, making it well suited for larger scientific applications studying magnetized matter-radiation interactions in solar and stellar interiors and atmospheres.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"74 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143836745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water-cooled (sub)-Neptunes get better gas mileage","authors":"Tatsuya Yoshida, Eric Gaidos","doi":"10.1051/0004-6361/202553667","DOIUrl":"https://doi.org/10.1051/0004-6361/202553667","url":null,"abstract":"The demographics of sub-Jovian planets around low-mass stars is dominated by populations of sub-Neptunes and super-Earths, distinguished by the presence or absence of envelopes of volatiles with a low molecular weight, that is, H<sub>2<sub/>, He, and H<sub>2<sub/>O. The current paradigm is that sub-Neptunes on close-in orbits evolve into super-Earths via atmospheric escape driven by high-energy stellar irradiation. We used an integrated hydrodynamic-radiation-chemical network model of the outflow to demonstrate that this escape is modulated by the abundance of H<sub>2<sub/>O, which is an efficient infrared coolant. Increasing the H<sub>2<sub/>O/H<sub>2<sub/> at the base of the flow induces a 1 dex decline in the escape rate, with definitive consequences for the retention of envelopes over Gyr. We show that saturation limits on H<sub>2<sub/>O in the upper atmospheres of temperate sub-Neptunes could explain the paradoxical observation that these objects disappear more rapidly than their counterparts closer to their host stars. We also propose that the scarcity of sub-Neptunes around very low-mass stars could be related to the water-poor chemistry of their antecedent protoplanetary disks. Observations of atmospheric H<sub>2<sub/>O by <i>JWST<i/> as well as searches for atmospheric escape from younger planets using H and He lines could test these predictions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"22 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143836749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pluto’s atmosphere gas and haze composition from JWST/MIRI spectroscopy","authors":"E. Lellouch, I. Wong, P. Lavvas, T. Bertrand, G. Villanueva, J. Stansberry, B. Holler, N. Pinilla-Alonso, F. Merlin, A. C. Souza-Feliciano, K. Murray","doi":"10.1051/0004-6361/202453619","DOIUrl":"https://doi.org/10.1051/0004-6361/202453619","url":null,"abstract":"&lt;i&gt;Context.&lt;i/&gt; Pluto possesses a tenuous, time-variable, N&lt;sub&gt;2&lt;sub/&gt;-dominated atmosphere, with extensive haze. Previous spectroscopic observations from the ground at near-infrared (NIR) and submillimeter (submm) wavelengths and New Horizons in the ultraviolet (UV) have revealed a Titan-like atmosphere with rich N&lt;sub&gt;2&lt;sub/&gt;-CH&lt;sub&gt;4&lt;sub/&gt; photochemistry. The mid-infrared (MIR) range of Pluto’s spectrum, however, has remained out of reach thus far.&lt;i&gt;Aims.&lt;i/&gt; Taking advantage of JWST sensitivity, our goal is to obtain new insights into Pluto’s atmospheric gas and haze composition using mid-IR spectroscopy.&lt;i&gt;Methods.&lt;i/&gt; In May 2023, we used JWST/MIRI MRS to acquire a high signal-to-noise (S/N) spectrum of Pluto over 4.9–27 μm, finally opening up the MIR spectral range for Pluto. The data were analyzed with a standard radiative transfer code, including the solar and thermal components, and the gas and haze emission, using gas vertical distributions from photochemical models as templates.&lt;i&gt;Results.&lt;i/&gt; The Pluto spectrum consists of the superposition of solar light reflected off Pluto’s surface, surface thermal emission, gas thermal and non-thermal emission, and haze emission. The solar reflected component shows absorption by CH&lt;sub&gt;4&lt;sub/&gt;, CH&lt;sub&gt;3&lt;sub/&gt;D, and C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;4&lt;sub/&gt; surface ices. Spectral signatures of C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;6&lt;sub/&gt;, C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt;, CH&lt;sub&gt;3&lt;sub/&gt;C&lt;sub&gt;2&lt;sub/&gt;H, and C&lt;sub&gt;4&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt; gases are strongly detected over 12–16 μm, broadly probing the stratopause region (altogether spanning 15–100 km). Unexpectedly, we also detect fluorescence (non-LTE) emission from gas CH&lt;sub&gt;4&lt;sub/&gt; (&lt;i&gt;ν&lt;i/&gt;&lt;sub&gt;4&lt;sub/&gt; and hot bands) and CH&lt;sub&gt;3&lt;sub/&gt;D (&lt;i&gt;ν&lt;i/&gt;&lt;sub&gt;6&lt;sub/&gt; band) in the 7–9 μm range, indicating excitation temperatures that are much higher than Pluto’s atmosphere kinetic temperature. The C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;6&lt;sub/&gt; abundance agrees very well with photochemical models, but those of CH&lt;sub&gt;3&lt;sub/&gt;C&lt;sub&gt;2&lt;sub/&gt;H, and C&lt;sub&gt;4&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt; are about five and ten times lower than model predictions, respectively. The C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt; 12.9–14.7 μm emission (&lt;i&gt;ν&lt;i/&gt;&lt;sub&gt;5&lt;sub/&gt;) is imperfectly fit and may point to a less steep C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt; profile than in model predictions or (perhaps more likely) to non-LTE effects on this band. Remarkably, C&lt;sub&gt;2&lt;sub/&gt;HD is detected at 14.75 μm, yielding a (D/H)&lt;sub&gt;C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt;&lt;sub/&gt; ratio equal to (3±1) terrestrial. Also, HCN has been tentatively observed and upper limits on several other gases (C&lt;sub&gt;2&lt;sub/&gt;H&lt;sub&gt;4&lt;sub/&gt;, C&lt;sub&gt;3&lt;sub/&gt;H&lt;sub&gt;8&lt;sub/&gt;, C&lt;sub&gt;6&lt;sub/&gt;H&lt;sub&gt;6&lt;sub/&gt;, HC&lt;sub&gt;3&lt;sub/&gt;N, and CO&lt;sub&gt;2&lt;sub/&gt;) are obtained. The haze emission is clearly present over 13–20 μm and characterized by emission peaks at 15.45 μm, 14.58 μm, and maybe 13.60 μm. The haze spectrum is very different from Titan’s and points to the presence of pure or mixed ices (e.g., C&lt;sub&gt;4&lt;sub/&gt;H&lt;sub&gt;2&lt;sub/&gt;, C&lt;sub&gt;6&lt;sub/&gt;H&lt;sub&gt;6&lt;sub/&gt;),","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143836742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An automatic detection method for small size dwarf galaxy candidates","authors":"Haifeng Yang, Boyu Zhang, Jianghui Cai, Han Qu, Aiyu Zheng, Jing Hao, Xin Chen, Xujun Zhao, Yaling Xun","doi":"10.1051/0004-6361/202453042","DOIUrl":"https://doi.org/10.1051/0004-6361/202453042","url":null,"abstract":"The missing satellite problem remains a central issue of the Lambda cold dark matter (ΛCDM) model. On a small scale, the number of observed dwarf galaxies is still fewer than the number predicted by existing theories. Therefore, finding fainter dwarf galaxies in deeper images is crucial for refining the existing theoretical framework. In this study, we propose an end-to-end automatic identification scheme for small size and faint dwarf galaxies based on the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys photometric images, and we provide a batch of dwarf galaxy candidates. We develop a dwarf galaxy automatic detection model, YOLO-DG, based on the YOLOv7 framework, and we achieve a precision of 88.2% and a recall of 89.1% on the test set. We identify 742 251 dwarf galaxy candidates across the entire DESI DR9 footprint using YOLO-DG, with their spectral redshifts concentrated in the range of 0–0.1. The faintest dwarf galaxy candidates detected by YOLO-DG have magnitudes of 31.61, 27.62, and 32.78 mag in the <i>g<i/>, <i>r<i/>, and <i>z<i/> bands, respectively. We identify 95 230 local volume dwarf galaxy candidates, 33 of which are identified based on spectral redshift. The half-light radius of the smallest local volume dwarf galaxy candidate is 0.31 arcsec. Finally, we provide a complete catalogue of local volume dwarf galaxy candidates.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"115 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143836738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"COSMOS-Web: A history of galaxy migrations over the stellar mass–star formation rate plane","authors":"R. C. Arango-Toro, O. Ilbert, L. Ciesla, M. Shuntov, G. Aufort, W. Mercier, C. Laigle, M. Franco, M. Bethermin, D. Le Borgne, Y. Dubois, H. J. McCracken, L. Paquereau, M. Huertas-Company, J. Kartaltepe, C. M. Casey, H. Akins, N. Allen, I. Andika, M. Brinch, N. E. Drakos, A. Faisst, G. Gozaliasl, S. Harish, A. Kaminsky, A. Koekemoer, V. Kokorev, D. Liu, G. Magdis, C. L. Martin, T. Moutard, J. Rhodes, R. M. Rich, B. Robertson, D. B. Sanders, K. Sheth, M. Talia, S. Toft, L. Tresse, F. Valentino, A. Vijayan, J. Weaver","doi":"10.1051/0004-6361/202452519","DOIUrl":"https://doi.org/10.1051/0004-6361/202452519","url":null,"abstract":"<i>Context.<i/> The stellar mass-star formation rate (<i>M<i/><sub>⋆<sub/> − SFR) plane is an essential diagnostic to separate galaxy populations. However, we still lack a clear picture of how galaxies move within this plane along cosmic time.<i>Aims.<i/> This study aims to provide an observational description of galaxy migrations in the <i>M<i/><sub>⋆<sub/> − SFR plane based on the reconstructed star formation histories (SFH) of a sample of galaxies at redshift <i>z<i/> < 4. Ultimately, this study seeks to provide insight into physical processes driving star formation.<i>Methods.<i/> We used data from the COSMOS field, which provides extensive multi-wavelength coverage. We selected a sample of 299131 galaxies at <i>z<i/> < 4 with the COSMOS-Web NIRCam data at a magnitude of <i>m<i/><sub>F444W<sub/> < 27 over a large area of 0.54 deg<sup>2<sup/>. We utilized the SED modeling code CIGALE, which incorporates non-parametric SFHs, to derive the physical properties and reconstruct the SFHs of this galaxy sample. To characterize the SFHs and interpret the galaxies’ movements on the <i>M<i/><sub>⋆<sub/> − SFR plane, for each galaxy we also defined a migration vector in order to track the direction (Φ<sub>Δ<i>t<i/><sub/>[deg]) and velocity norm (<i>r<i/><sub>Δ<i>t<i/><sub/>[dex/Gyr]) of the evolutionary path over the <i>M<i/><sub>⋆<sub/> − SFR plane. We quantified the quality at which these migration vectors can be reconstructed using the HORIZON-AGN cosmological hydrodynamical simulation.<i>Results.<i/> We find that galaxies within the main sequence exhibit the lowest amplitude in their migration and a large dispersion in the direction of their movements. We interpret this result as galaxies oscillating within the galaxy main sequence. By using their migration vectors to find the position of main-sequence progenitors, we obtained that most of the progenitors were already on the main sequence as defined one billion years earlier. We find that galaxies within the starburst or passive region of the <i>M<i/><sub>⋆<sub/> − SFR plane have very homogeneous properties in terms of recent SFH (< 1 Gyr). Starburst galaxies assembled half of their stellar mass within the last 350 Myr, and this population originates from the main sequence. Galaxies in the passive region of the plane show a homogeneous declining SFH over the full considered redshift range. We identified massive galaxies already in the passive region at 3.5 < <i>z<i/> < 4, and their number density increases continuously with cosmic time. The progenitors of passive galaxies are distributed over a large range of SFRs, with less than 20% of passive galaxies being starburst 1 Gyr earlier, thus shedding light on rapid quenching channels.<i>Conclusions.<i/> Using reconstructed SFHs up to <i>z<i/> < 4, we propose a coherent picture of how galaxies migrate over cosmic time in the <i>M<i/><sub>⋆<sub/> − SFR plane, highlighting the connection between major phases in the SFH.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"26 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143836737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The infrared counterpart and proper motion of magnetar SGR 0501+4516","authors":"A. A. Chrimes, A. J. Levan, J. D. Lyman, A. Borghese, V. S. Dhillon, P. Esposito, M. Fraser, A. S. Fruchter, D. Götz, R. A. Hounsell, G. L. Israel, C. Kouveliotou, S. Mereghetti, R. P. Mignani, R. Perna, N. Rea, I. Skillen, D. Steeghs, N. R. Tanvir, K. Wiersema, N. J. Wright, S. Zane","doi":"10.1051/0004-6361/202453479","DOIUrl":"https://doi.org/10.1051/0004-6361/202453479","url":null,"abstract":"<i>Aims.<i/> Soft gamma repeaters (SGRs) are highly magnetised neutron stars (magnetars) notable for their gamma-ray and X-ray outbursts. We used near-infrared (NIR) imaging of SGR 0501+4516 in the days, weeks, and years after its 2008 outburst to characterise the multi-wavelength emission, and to obtain a proper motion from our long temporal baseline observations.<i>Methods.<i/> We present short- and long-term monitoring of the IR counterpart of SGR 0501+4516 and a measurement of its proper motion. Unlike most magnetars, the source has only moderate foreground extinction with minimal crowding. Our observations began only ∼2 hours after the first activation of SGR 0501+4516 in August 2008 and continued for ∼4 years, including two epochs of <i>Hubble<i/> Space Telescope (HST) imaging. The proper motion constraint was improved using a third HST epoch from 10 years later.<i>Results.<i/> The NIR and X-rays faded slowly during the first week, which was followed by a steeper power-law decay. The behaviour is satisfactorily fit by a broken power law. Three epochs of HST imaging with a 10-year baseline allowed us to determine the quiescent level and to measure a proper motion of <i>μ<i/> = 5.4 ± 0.6 mas yr<sup>−1<sup/>. This corresponds to a low transverse peculiar velocity of <i>v<i/> ≃ 51 ± 14 km s<sup>−1<sup/> (at 2 kpc). The magnitude and direction of the proper motion rules out supernova remnant HB9 as the birth site. We can find no other supernova remnants or groups of massive stars within the region traversed by SGR 0501+4516 during its characteristic lifetime (∼20 kyr).<i>Conclusions.<i/> Our observations of SGR 0501+4516 suggest three possibilities: that some magnetars are significantly older than expected, that their progenitors produce low supernova ejecta masses, or that they can be formed through accretion-induced collapse or low-mass neutron star mergers. Although the progenitor of SGR 0501+4516 remains unclear, we propose that SGR 0501+4516 is the best Galactic candidate for a magnetar formed through a mechanism other than massive star core-collapse.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"953 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143836748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}