Pub Date : 2026-04-13DOI: 10.3847/1538-4357/ae4a9a
Shrihan Agarwal, Xiaosheng Huang, W. Sheu, C.J. Storfer, M. Tamargo-Arizmendi, S. Tabares-Tarquinio, D.J. Schlegel, G. Aldering, A. Bolton, A. Cikota, Arjun Dey, A. Filipp, E. Jullo, K.J. Kwon, S. Perlmutter, Y. Shu, E. Sukay, N. Suzuki, J. Aguilar, S. Ahlen, S. BenZvi, D. Brooks, T. Claybaugh, P. Doel, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, K. Honscheid, M. Ishak, S. Juneau, R. Kehoe, T. Kisner, S. E. Koposov, A. Lambert, M. Landriau, L. Le Guillou, A. de la Macorra, A. Meisner, R. Miquel, J. Moustakas, A. D. Myers, C. Poppett, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, M. Schubnell, D. Sprayberry, G. Tarlé, B. A. Weaver and H. Zou
We present spectroscopic data of strong lenses and their source galaxies using the Keck Near-Infrared Echellette Spectrometer (NIRES) and the Dark Energy Spectroscopic Instrument (DESI), providing redshifts necessary for nearly all strong-lensing applications with these systems, especially the extraction of physical parameters from lensing modeling. These strong lenses were found in the DESI Legacy Imaging Surveys using residual neural networks and followed up by our Hubble Space Telescope program, with all systems displaying unambiguous lensed arcs. With NIRES, we target eight lensed sources at redshifts difficult to measure in the optical range and determine the source redshifts for six, between zs = 1.675 and 3.332. DESI observed one of the remaining source redshifts, as well as an additional source redshift within the six systems. The two systems with nondetections by NIRES were observed for a considerably shorter 600 s at high airmass. Combining NIRES infrared spectroscopy with optical spectroscopy from our DESI Strong Lensing Secondary Target Program, these results provide the complete lens and source redshifts for six systems, a resource for refining automated strong lens searches in future deep- and wide-field imaging surveys and addressing a range of questions in astrophysics and cosmology.
{"title":"DESI Strong Lens Foundry. III. Keck Spectroscopy for Strong Lenses Discovered Using Residual Neural Networks","authors":"Shrihan Agarwal, Xiaosheng Huang, W. Sheu, C.J. Storfer, M. Tamargo-Arizmendi, S. Tabares-Tarquinio, D.J. Schlegel, G. Aldering, A. Bolton, A. Cikota, Arjun Dey, A. Filipp, E. Jullo, K.J. Kwon, S. Perlmutter, Y. Shu, E. Sukay, N. Suzuki, J. Aguilar, S. Ahlen, S. BenZvi, D. Brooks, T. Claybaugh, P. Doel, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, K. Honscheid, M. Ishak, S. Juneau, R. Kehoe, T. Kisner, S. E. Koposov, A. Lambert, M. Landriau, L. Le Guillou, A. de la Macorra, A. Meisner, R. Miquel, J. Moustakas, A. D. Myers, C. Poppett, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, M. Schubnell, D. Sprayberry, G. Tarlé, B. A. Weaver and H. Zou","doi":"10.3847/1538-4357/ae4a9a","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a9a","url":null,"abstract":"We present spectroscopic data of strong lenses and their source galaxies using the Keck Near-Infrared Echellette Spectrometer (NIRES) and the Dark Energy Spectroscopic Instrument (DESI), providing redshifts necessary for nearly all strong-lensing applications with these systems, especially the extraction of physical parameters from lensing modeling. These strong lenses were found in the DESI Legacy Imaging Surveys using residual neural networks and followed up by our Hubble Space Telescope program, with all systems displaying unambiguous lensed arcs. With NIRES, we target eight lensed sources at redshifts difficult to measure in the optical range and determine the source redshifts for six, between zs = 1.675 and 3.332. DESI observed one of the remaining source redshifts, as well as an additional source redshift within the six systems. The two systems with nondetections by NIRES were observed for a considerably shorter 600 s at high airmass. Combining NIRES infrared spectroscopy with optical spectroscopy from our DESI Strong Lensing Secondary Target Program, these results provide the complete lens and source redshifts for six systems, a resource for refining automated strong lens searches in future deep- and wide-field imaging surveys and addressing a range of questions in astrophysics and cosmology.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147666474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-13DOI: 10.3847/1538-4357/ae5707
Wenlang He, Ping Zhou and Bingqiu Chen
Magnetars are highly magnetized neutron stars whose evolution and radiation are governed by the decay and/or reconfiguration of their magnetic fields. The origin of magnetars remains an open question, with proposed progenitor scenarios including core collapse (CC) of very massive stars (≥25 M⊙) or not very massive stars (8 M⊙ < M* < 25 M⊙), mergers of stellar systems, and accretion-induced collapse of white dwarfs. Investigating the environments of magnetars can offer valuable clues to this issue. In this work, we study the local (radius of 0 87, ∼100 pc at 6.6 kpc) stellar environment of SGR 1935+2154, which is spatially associated with the supernova remnant (SNR) G57.2+0.8, based on astrometry from Gaia DR3 and multiband photometry from optical to infrared. We discover that the upper limit of the surface density of massive stars around SGR 1935+2154 is only a quarter of that of the solar neighborhood, where the star formation rate is modest in the Galaxy. This quiet environment implies that the magnetar was likely formed by the CC of either a not very massive star or a binary merger product rather than the CC of a very massive star. Although alternative channels cannot be excluded, their probabilities may be substantially lower. The studies of magnetars associated with SNRs consistently favor not very massive progenitors, implying that such progenitors may produce a considerable fraction of magnetars. We also backtrack the trajectories of SGR 1935+2154 and its surrounding stars to search for its potential massive companions, yet no such companions are found.
{"title":"The Magnetar SGR 1935+2154’s Quiet Local Environment: Clues for Its Progenitor","authors":"Wenlang He, Ping Zhou and Bingqiu Chen","doi":"10.3847/1538-4357/ae5707","DOIUrl":"https://doi.org/10.3847/1538-4357/ae5707","url":null,"abstract":"Magnetars are highly magnetized neutron stars whose evolution and radiation are governed by the decay and/or reconfiguration of their magnetic fields. The origin of magnetars remains an open question, with proposed progenitor scenarios including core collapse (CC) of very massive stars (≥25 M⊙) or not very massive stars (8 M⊙ < M* < 25 M⊙), mergers of stellar systems, and accretion-induced collapse of white dwarfs. Investigating the environments of magnetars can offer valuable clues to this issue. In this work, we study the local (radius of 0 87, ∼100 pc at 6.6 kpc) stellar environment of SGR 1935+2154, which is spatially associated with the supernova remnant (SNR) G57.2+0.8, based on astrometry from Gaia DR3 and multiband photometry from optical to infrared. We discover that the upper limit of the surface density of massive stars around SGR 1935+2154 is only a quarter of that of the solar neighborhood, where the star formation rate is modest in the Galaxy. This quiet environment implies that the magnetar was likely formed by the CC of either a not very massive star or a binary merger product rather than the CC of a very massive star. Although alternative channels cannot be excluded, their probabilities may be substantially lower. The studies of magnetars associated with SNRs consistently favor not very massive progenitors, implying that such progenitors may produce a considerable fraction of magnetars. We also backtrack the trajectories of SGR 1935+2154 and its surrounding stars to search for its potential massive companions, yet no such companions are found.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147666538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-13DOI: 10.3847/1538-4357/ae5531
A.P. Sainterme and Fatima Ebrahimi
Non-axisymmetric, flow-driven instabilities in the incompressible Hall-MHD model are studied in a differentially rotating cylindrical plasma. It is found that, in the Hall-MHD regime, both whistler waves and ion-cyclotron waves can extract energy from the flow shear, resulting in two distinct branches of global instability. The non-axisymmetric whistler modes grow significantly faster than non-axisymmetric, ideal MHD modes. A discussion of the global whistler instability mechanism is presented in the large-ion-skin-depth, “electron-MHD” limit. When the magnetic field is azimuthal, a subset of the whistler modes having zero axial wave number are uncovered to be destabilized by the “corotation amplifier” mechanism. It is observed that the effect of the Hall term on the non-axisymmetric modes can be appreciable when di is on the order of a few percent of the width of the cylindrical annulus. Distinct global modes emerge in the strong Hall-MHD regime at significantly stronger magnetic fields than those required for unstable global MHD modes, as the Hall effect weakens the stabilizing “field-line bending” by decoupling ion motion from the magnetic field. These global non-axisymmetric modes may play an important role in weakly ionized accretion disks.
{"title":"Global Non-axisymmetric Hall Instabilities in a Rotating Plasma","authors":"A.P. Sainterme and Fatima Ebrahimi","doi":"10.3847/1538-4357/ae5531","DOIUrl":"https://doi.org/10.3847/1538-4357/ae5531","url":null,"abstract":"Non-axisymmetric, flow-driven instabilities in the incompressible Hall-MHD model are studied in a differentially rotating cylindrical plasma. It is found that, in the Hall-MHD regime, both whistler waves and ion-cyclotron waves can extract energy from the flow shear, resulting in two distinct branches of global instability. The non-axisymmetric whistler modes grow significantly faster than non-axisymmetric, ideal MHD modes. A discussion of the global whistler instability mechanism is presented in the large-ion-skin-depth, “electron-MHD” limit. When the magnetic field is azimuthal, a subset of the whistler modes having zero axial wave number are uncovered to be destabilized by the “corotation amplifier” mechanism. It is observed that the effect of the Hall term on the non-axisymmetric modes can be appreciable when di is on the order of a few percent of the width of the cylindrical annulus. Distinct global modes emerge in the strong Hall-MHD regime at significantly stronger magnetic fields than those required for unstable global MHD modes, as the Hall effect weakens the stabilizing “field-line bending” by decoupling ion motion from the magnetic field. These global non-axisymmetric modes may play an important role in weakly ionized accretion disks.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147666529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-12DOI: 10.3847/1538-4357/ae4a29
Ryan Sponzilli, Leslie W. Looney, John J. Tobin, Frankie J. Encalada, Austen Fourkas, Hector Arce, Erin Cox, James Di Francesco, Nicole Karnath, Zhi-Yun Li, Nadia Murillo, Stella Offner, Sarah Sadavoy and Rajeeb Sharma
Understanding the formation pathway for close-companion protostars is central to unraveling the processes that govern stellar multiplicity and very early star formation. We analyze a large sample of 51 Class 0/I close-companion protostellar systems, of which 38 show detectable outflows, yielding 42 measured outflows used in our analysis. We use Atacama Large Millimeter/submillimeter Array observations of 11 systems in Perseus and 40 systems in Orion. These companions formed either directly at these small scales (≲500 au separations) via disk fragmentation or at larger scales (>1000 au separations) via turbulent fragmentation followed by inward migration. Because of differences in formation mechanism, the former is expected to have preferentially aligned disks and outflows, whereas the latter is expected to show no preferred alignment. The relative prevalence of these formation pathways remains uncertain, yet it is critical to forming a comprehensive picture of star formation. We examine the distribution of position angles (PAs) of companion protostars relative to the PAs of their molecular outflows. The outflow, as traced by 12CO (J = 2 → 1), is a useful proxy for the angular momentum of the system, expected to be orthogonal to the binary orbital plane. We use a simple model to account for a random sampling of inclination and orbital phase in each system, finding that the observations are consistent with a distribution where the outflows are preferentially orthogonal to the companions. Based on this analysis, we suggest disk fragmentation is the dominant formation pathway for close-companion protostellar systems.
{"title":"Protostellar Outflows Shed Light on the Dominant Close Companion Star Formation Pathways","authors":"Ryan Sponzilli, Leslie W. Looney, John J. Tobin, Frankie J. Encalada, Austen Fourkas, Hector Arce, Erin Cox, James Di Francesco, Nicole Karnath, Zhi-Yun Li, Nadia Murillo, Stella Offner, Sarah Sadavoy and Rajeeb Sharma","doi":"10.3847/1538-4357/ae4a29","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a29","url":null,"abstract":"Understanding the formation pathway for close-companion protostars is central to unraveling the processes that govern stellar multiplicity and very early star formation. We analyze a large sample of 51 Class 0/I close-companion protostellar systems, of which 38 show detectable outflows, yielding 42 measured outflows used in our analysis. We use Atacama Large Millimeter/submillimeter Array observations of 11 systems in Perseus and 40 systems in Orion. These companions formed either directly at these small scales (≲500 au separations) via disk fragmentation or at larger scales (>1000 au separations) via turbulent fragmentation followed by inward migration. Because of differences in formation mechanism, the former is expected to have preferentially aligned disks and outflows, whereas the latter is expected to show no preferred alignment. The relative prevalence of these formation pathways remains uncertain, yet it is critical to forming a comprehensive picture of star formation. We examine the distribution of position angles (PAs) of companion protostars relative to the PAs of their molecular outflows. The outflow, as traced by 12CO (J = 2 → 1), is a useful proxy for the angular momentum of the system, expected to be orthogonal to the binary orbital plane. We use a simple model to account for a random sampling of inclination and orbital phase in each system, finding that the observations are consistent with a distribution where the outflows are preferentially orthogonal to the companions. Based on this analysis, we suggest disk fragmentation is the dominant formation pathway for close-companion protostellar systems.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147664161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-12DOI: 10.3847/1538-4357/ae5521
Lizhong Zhang, 力中 张, James M. Stone, Christopher J. White, Shane W. Davis, Yan-Fei Jiang, 燕飞 姜 and Patrick D. Mullen
We present a comprehensive analysis of super-Eddington black hole accretion simulations that solve the GRMHD equations coupled with angle-discretized radiation transport. The simulations span a range of accretion rates, two black hole spins, and two magnetic field topologies, and include resolution studies as well as comparisons with nonradiative models. Super-Eddington accretion flows consistently develop geometrically thick disks supported by radiation pressure, regardless of magnetic field configuration. Radiation generated in the inner disk drives substantial outflows, forming conical funnel regions that limit photon escape and result in very low radiation efficiency. The accretion flows are highly turbulent, with thermal energy transport dominated by radiation advection rather than diffusion. Angular momentum is primarily carried outward by Maxwell stress, with turbulent Reynolds stress playing a subdominant role. Both strong and weak jets are produced. Strong jets arise from sufficient net vertical magnetic flux and rapid black hole spin, and they can effectively evacuate the funnel, enabling radiation to escape through strong geometric beaming. In contrast, weak jets fail to clear the funnel, which becomes obscured by radiation-driven outflows and leads to distinct observational signatures. Spiral structures are observed in the plunging region, behaving like density waves. These super-Eddington models are applicable to a variety of astronomical systems, including ultraluminous X-ray sources, little red dots, and black hole transients.
{"title":"Radiation GRMHD Models of Accretion onto Stellar-mass Black Holes. II. Super-Eddington Accretion","authors":"Lizhong Zhang, 力中 张, James M. Stone, Christopher J. White, Shane W. Davis, Yan-Fei Jiang, 燕飞 姜 and Patrick D. Mullen","doi":"10.3847/1538-4357/ae5521","DOIUrl":"https://doi.org/10.3847/1538-4357/ae5521","url":null,"abstract":"We present a comprehensive analysis of super-Eddington black hole accretion simulations that solve the GRMHD equations coupled with angle-discretized radiation transport. The simulations span a range of accretion rates, two black hole spins, and two magnetic field topologies, and include resolution studies as well as comparisons with nonradiative models. Super-Eddington accretion flows consistently develop geometrically thick disks supported by radiation pressure, regardless of magnetic field configuration. Radiation generated in the inner disk drives substantial outflows, forming conical funnel regions that limit photon escape and result in very low radiation efficiency. The accretion flows are highly turbulent, with thermal energy transport dominated by radiation advection rather than diffusion. Angular momentum is primarily carried outward by Maxwell stress, with turbulent Reynolds stress playing a subdominant role. Both strong and weak jets are produced. Strong jets arise from sufficient net vertical magnetic flux and rapid black hole spin, and they can effectively evacuate the funnel, enabling radiation to escape through strong geometric beaming. In contrast, weak jets fail to clear the funnel, which becomes obscured by radiation-driven outflows and leads to distinct observational signatures. Spiral structures are observed in the plunging region, behaving like density waves. These super-Eddington models are applicable to a variety of astronomical systems, including ultraluminous X-ray sources, little red dots, and black hole transients.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147664164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-12DOI: 10.3847/1538-4357/ae5527
James N. Reeves, Shoji Ogawa, Tracey J. Turner, Valentina Braito, Satoshi Yamada, Steven B. Kraemer, Hirofumi Noda, Anna Trindade Falcão, Martin Elvis and Giuseppina Fabbiano
NGC 4051 is a nearby (16.7 Mpc), Narrow Line Seyfert 1 galaxy (NLS1), which has a low black hole mass of 106M⊙. It is also known for its rapid X-ray variability, on timescales of kiloseconds, and has a complex, multicomponent wind in both the soft X-ray and Fe K bands. Here we present the first high-resolution XRISM Resolve spectrum of NGC 4051, which was captured in a historically bright state for a 150 ks exposure. XRISM resolves two blueshifted Fe K shell absorption troughs in the mean spectrum, which can be ascribed to H-like iron and arises from two outflow components with outflow velocities of 0.025c and 0.04c. A time-dependent spectral analysis shows that the iron K absorption is variable on timescales of less than a day, increasing in velocity over the duration of the observation. The velocity changes may be explained either by the passage of two separate transiting absorbers, of different velocities, or by a single accelerating outflow of approximately constant column density. In the latter case, the wind acceleration is likely to be too large to be caused by radiation pressure, and instead, magnetic driving is favored to accelerate the wind up to 0.04c. The outflow can originate from an accretion disk wind, whose kinetic power is sub-Eddington, in contrast to recent examples of winds from powerful, luminous quasars observed by XRISM.
NGC 4051是一个邻近的（16.7 Mpc）窄线塞弗特1星系（NLS1），它的黑洞质量很低，只有106米⊙。它也以其快速的x射线变化而闻名，在千秒的时间尺度上，并且在软x射线和铁K波段都有复杂的多组分风。在这里，我们展示了NGC 4051的第一个高分辨率XRISM Resolve光谱，它是在150ks的曝光下在历史上最亮的状态下拍摄的。XRISM在平均光谱中分辨出两个蓝移的Fe - K壳吸收波谷，可归因于类h铁，由两个流出成分产生，流出速度分别为0.025c和0.04c。随时间变化的光谱分析表明，铁K吸收在不到一天的时间尺度上是可变的，在观察的持续时间内速度增加。速度的变化可以解释为两个不同速度的独立过路吸收器的通过，或者是一个近似恒定柱密度的单一加速流出。在后一种情况下，风的加速度可能太大，而不是由辐射压力引起的，相反，磁驱动更倾向于将风加速到0.04c。流出物可能来自吸积盘风，其动能低于爱丁顿，这与XRISM最近观测到的来自强大明亮类星体的风形成了对比。
{"title":"Winds of Change: XRISM Resolve X-Ray Spectroscopy of NGC 4051","authors":"James N. Reeves, Shoji Ogawa, Tracey J. Turner, Valentina Braito, Satoshi Yamada, Steven B. Kraemer, Hirofumi Noda, Anna Trindade Falcão, Martin Elvis and Giuseppina Fabbiano","doi":"10.3847/1538-4357/ae5527","DOIUrl":"https://doi.org/10.3847/1538-4357/ae5527","url":null,"abstract":"NGC 4051 is a nearby (16.7 Mpc), Narrow Line Seyfert 1 galaxy (NLS1), which has a low black hole mass of 106M⊙. It is also known for its rapid X-ray variability, on timescales of kiloseconds, and has a complex, multicomponent wind in both the soft X-ray and Fe K bands. Here we present the first high-resolution XRISM Resolve spectrum of NGC 4051, which was captured in a historically bright state for a 150 ks exposure. XRISM resolves two blueshifted Fe K shell absorption troughs in the mean spectrum, which can be ascribed to H-like iron and arises from two outflow components with outflow velocities of 0.025c and 0.04c. A time-dependent spectral analysis shows that the iron K absorption is variable on timescales of less than a day, increasing in velocity over the duration of the observation. The velocity changes may be explained either by the passage of two separate transiting absorbers, of different velocities, or by a single accelerating outflow of approximately constant column density. In the latter case, the wind acceleration is likely to be too large to be caused by radiation pressure, and instead, magnetic driving is favored to accelerate the wind up to 0.04c. The outflow can originate from an accretion disk wind, whose kinetic power is sub-Eddington, in contrast to recent examples of winds from powerful, luminous quasars observed by XRISM.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"110 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147664165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-12DOI: 10.3847/1538-4357/ae4e2c
Pradeep Kayshap, Petr Jelínek, B. Suresh Babu, Ashok Kumar Baral and Yuandeng Shen
We aim to investigate the blowout jet-like prominence eruption, which occurred on 2023 October 6, with the help of imaging and spectroscopic observations. Firstly, the prominence rises slowly at a speed of 33 km s−1, followed by a fast rise (i.e., 338 km s−1). Later, the northern leg breaks completely, and the eruption forms the blowout jet. The jet consists of different plasma threads, which show a range of upflow (i.e., 125–593 km s−1) and downflow velocities (i.e., 43–158 km s−1). The jet plasma column exhibits transverse oscillations, and this motion (untwisting motion) propagates at a speed of 267 km s−1. This transverse motion is consistent with being Alfvén waves. The transverse motion has a time period, amplitude, and transverse velocity of 1332 s, 26.19 Mm, and 126.18 ± 7.27 km s−1, respectively, and this transverse oscillation decays over time. Interestingly, the different plasma threads within the jet’s body exhibit decayless transverse oscillations, and these decayless oscillations are related to the main decaying transverse oscillation. The transverse velocity of these decayless oscillations ranges from 66 to 30 km s−1, the amplitudes from 8.52 to 2.74 Mm, and periods from 811 to 406 s. In addition, the spectroscopic analysis reveals that Si iv lines are forming under optically thick conditions in high electron density regions (i.e., near the base of the blowout jet). Lastly, we mention that two weak C-class flares occurred during this event, and further, one coronal mass ejection also occurred, which propagated at a speed of ∼250 km s−1.
我们的目标是利用成像和光谱观测来研究2023年10月6日发生的喷流状日珥喷发。首先，日珥以33 km s−1的速度缓慢上升，然后快速上升（即338 km s−1）。后来，北支完全断裂，火山喷发形成喷流。喷流由不同的等离子体线组成，呈现出上升（即125-593 km s - 1）和下降（即43-158 km s - 1）的速度范围。射流等离子体柱表现出横向振荡，这种运动（解扭运动）以267 km s−1的速度传播。这种横向运动与阿尔夫海姆波一致。横向运动的时间周期、振幅和横向速度分别为1332 s、26.19 Mm和126.18±7.27 km s−1，并且这种横向振荡随时间衰减。有趣的是，射流体内不同的等离子体线表现出无衰减横向振荡，这些无衰减振荡与主衰减横向振荡有关。这些无衰减振荡的横向速度范围为66 ~ 30 km s−1，振幅范围为8.52 ~ 2.74 Mm，周期为811 ~ 406 s。此外，光谱分析表明，在高电子密度区域（即喷吹射流底部附近）的光学厚条件下形成了Si iv线。最后，我们提到在这次事件中发生了两个弱c级耀斑，此外，还发生了一次日冕物质抛射，其传播速度为~ 250 km s−1。
{"title":"Kinematics and Untwisting Motion of an Intriguing Jet-like Prominence Eruption","authors":"Pradeep Kayshap, Petr Jelínek, B. Suresh Babu, Ashok Kumar Baral and Yuandeng Shen","doi":"10.3847/1538-4357/ae4e2c","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4e2c","url":null,"abstract":"We aim to investigate the blowout jet-like prominence eruption, which occurred on 2023 October 6, with the help of imaging and spectroscopic observations. Firstly, the prominence rises slowly at a speed of 33 km s−1, followed by a fast rise (i.e., 338 km s−1). Later, the northern leg breaks completely, and the eruption forms the blowout jet. The jet consists of different plasma threads, which show a range of upflow (i.e., 125–593 km s−1) and downflow velocities (i.e., 43–158 km s−1). The jet plasma column exhibits transverse oscillations, and this motion (untwisting motion) propagates at a speed of 267 km s−1. This transverse motion is consistent with being Alfvén waves. The transverse motion has a time period, amplitude, and transverse velocity of 1332 s, 26.19 Mm, and 126.18 ± 7.27 km s−1, respectively, and this transverse oscillation decays over time. Interestingly, the different plasma threads within the jet’s body exhibit decayless transverse oscillations, and these decayless oscillations are related to the main decaying transverse oscillation. The transverse velocity of these decayless oscillations ranges from 66 to 30 km s−1, the amplitudes from 8.52 to 2.74 Mm, and periods from 811 to 406 s. In addition, the spectroscopic analysis reveals that Si iv lines are forming under optically thick conditions in high electron density regions (i.e., near the base of the blowout jet). Lastly, we mention that two weak C-class flares occurred during this event, and further, one coronal mass ejection also occurred, which propagated at a speed of ∼250 km s−1.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147664580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-12DOI: 10.3847/1538-4357/ae4d13
Ellie K. H. Toguchi-Tani, Daniel R. Hey, Thomas de Boer, Peter M. Frinchaboy and Daniel Huber
The Sagittarius dwarf spheroidal galaxy (Sgr dSph) provides us with the unique opportunity to study an ongoing Galactic cannibalistic event between our Milky Way (MW) Galaxy and a satellite dwarf galaxy. Understanding this event crucially requires memberships and high-precision metallicities. Here, we present the first major membership star catalog of the Sgr dwarf core (≈140,000 sources) and Messier 54 (M54; ≈2000 sources) with positions, proper motions, and parallaxes from the third Gaia data release (DR3), supplemented with metallicities from the Apache Point Observatory Galactic Evolution Experiment (or APOGEE). We initially isolate the Sgr dwarf core and M54 spatially from prior literature positions. Using evolutionary subsamples separated within a color–magnitude diagram, we analyze the substructures of the Sgr core and infer its positional relationship with M54 within 5D phase space. A sample of MW stars from a similar Galactic latitude were used to identify contaminants and separate member stars from the core of the Sgr dSph and M54 using a Gaussian mixture model. We present the derived proper motions, parallaxes, and metallicities for these evolutionary subsamples and demonstrate the precision of our sample using red clump (RC) standard candles. We find distance moduli for the Sgr core and M54 of mag and mag, corresponding to heliocentric distances of kpc and kpc, respectively. Using RC distance analysis, our results imply that there is no separation between the Sgr core and M54. Finally, we describe the metallicity distributions of the evolved stars within these two systems, finding evidence for the infall scenario.
{"title":"Unveiling the Sagittarius Dwarf Spheroidal Galaxy Core with Gaia DR3: A Red Clump Distance Precise to 2%","authors":"Ellie K. H. Toguchi-Tani, Daniel R. Hey, Thomas de Boer, Peter M. Frinchaboy and Daniel Huber","doi":"10.3847/1538-4357/ae4d13","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4d13","url":null,"abstract":"The Sagittarius dwarf spheroidal galaxy (Sgr dSph) provides us with the unique opportunity to study an ongoing Galactic cannibalistic event between our Milky Way (MW) Galaxy and a satellite dwarf galaxy. Understanding this event crucially requires memberships and high-precision metallicities. Here, we present the first major membership star catalog of the Sgr dwarf core (≈140,000 sources) and Messier 54 (M54; ≈2000 sources) with positions, proper motions, and parallaxes from the third Gaia data release (DR3), supplemented with metallicities from the Apache Point Observatory Galactic Evolution Experiment (or APOGEE). We initially isolate the Sgr dwarf core and M54 spatially from prior literature positions. Using evolutionary subsamples separated within a color–magnitude diagram, we analyze the substructures of the Sgr core and infer its positional relationship with M54 within 5D phase space. A sample of MW stars from a similar Galactic latitude were used to identify contaminants and separate member stars from the core of the Sgr dSph and M54 using a Gaussian mixture model. We present the derived proper motions, parallaxes, and metallicities for these evolutionary subsamples and demonstrate the precision of our sample using red clump (RC) standard candles. We find distance moduli for the Sgr core and M54 of mag and mag, corresponding to heliocentric distances of kpc and kpc, respectively. Using RC distance analysis, our results imply that there is no separation between the Sgr core and M54. Finally, we describe the metallicity distributions of the evolved stars within these two systems, finding evidence for the infall scenario.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"68 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147664160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-12DOI: 10.3847/1538-4357/ae2e00
Konstantin V. Getman, Eric D. Feigelson, Vladimir S. Airapetian and Gordon P. Garmire
X-ray and ultraviolet (XUV) emission from young stars plays a critical role in shaping the evolution of planetary atmospheres and the conditions for habitability. To assess the long-term impact of high-energy stellar radiation, it is essential to empirically trace how X-ray luminosities and spectral hardness evolve during the first ≲1 Gyr, when atmospheric loss and chemical processing are most active. This study extends the X-ray activity–mass–age analysis of <25 Myr stars by K. V. Getman et al. (2022) to ages up to ∼750 Myr, using Gaia-based cluster memberships, new Chandra observations of five rich open clusters (∼45–100 Myr), and archival ROSAT and Chandra data for three older clusters (∼220–750 Myr). We find a mass-dependent decay in X-ray luminosity: solar-mass stars undergo a far more rapid and sustained decline, accompanied by coronal softening and the disappearance of hot plasma by ∼100 Myr, compared to their lower-mass siblings. These trends in solar-mass stars are likely linked to reduced magnetic dynamo efficiency and diminished ability to sustain large-scale, high-temperature coronal structures. The trends are significantly stronger than predicted by widely used XUV–rotation–age relations. The revised trends imply systematically lower rates of atmospheric mass loss and water photolysis, as well as altered ionization environments and chemical pathways relevant to the formation of prebiotic molecules, for planets in close orbits around solar analogs. These effects persist throughout at least the ≲750 Myr interval probed in this study.
{"title":"X-Ray Evolution of Young Stars: Early Dimming and Coronal Softening in Solar-mass Stars with Implications for Planetary Atmospheres","authors":"Konstantin V. Getman, Eric D. Feigelson, Vladimir S. Airapetian and Gordon P. Garmire","doi":"10.3847/1538-4357/ae2e00","DOIUrl":"https://doi.org/10.3847/1538-4357/ae2e00","url":null,"abstract":"X-ray and ultraviolet (XUV) emission from young stars plays a critical role in shaping the evolution of planetary atmospheres and the conditions for habitability. To assess the long-term impact of high-energy stellar radiation, it is essential to empirically trace how X-ray luminosities and spectral hardness evolve during the first ≲1 Gyr, when atmospheric loss and chemical processing are most active. This study extends the X-ray activity–mass–age analysis of <25 Myr stars by K. V. Getman et al. (2022) to ages up to ∼750 Myr, using Gaia-based cluster memberships, new Chandra observations of five rich open clusters (∼45–100 Myr), and archival ROSAT and Chandra data for three older clusters (∼220–750 Myr). We find a mass-dependent decay in X-ray luminosity: solar-mass stars undergo a far more rapid and sustained decline, accompanied by coronal softening and the disappearance of hot plasma by ∼100 Myr, compared to their lower-mass siblings. These trends in solar-mass stars are likely linked to reduced magnetic dynamo efficiency and diminished ability to sustain large-scale, high-temperature coronal structures. The trends are significantly stronger than predicted by widely used XUV–rotation–age relations. The revised trends imply systematically lower rates of atmospheric mass loss and water photolysis, as well as altered ionization environments and chemical pathways relevant to the formation of prebiotic molecules, for planets in close orbits around solar analogs. These effects persist throughout at least the ≲750 Myr interval probed in this study.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147664156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-12DOI: 10.3847/1538-4357/ae4d4a
Balpreet Kaur, Nissim Kanekar and J. Xavier Prochaska
We report Giant Metrewave Radio Telescope (GMRT) H i 21 cm imaging of NGC 4141, the host galaxy of FRB 20250316A at z = 0.0063. Our GMRT H i 21 cm images have spatial resolutions, at z ≈ 0.0063, of ≈0.48–8.0 kpc, and provide evidence for (i) a companion galaxy, LEDA 2582852, to the southwest, (ii) a nearby (27 kpc distant) H i cloud to the southwest, (iii) disturbances in the H i distributions of both NGC 4141 and LEDA 2582852, and (iv) high H i column densities in the southwestern outskirts of NGC 4141. A Sloan Digital Sky Survey spectrum yields a low metallicity and a high star formation rate (SFR) surface density in the southwestern disk of NGC 4141, and an Hα-based SFR estimate that is significantly higher than that at the same location from the Galaxy Evolution Explorer near-ultraviolet image, indicating a recent burst of star formation. The total SFR of NGC 4141 is also found to be higher via the Hα line than from the 1.4 GHz radio continuum. The above evidence indicates that NGC 4141 has recently (within the last ≈3 Myr) acquired metal-poor gas, via either a merger or accretion, that resulted in the southwestern starburst and that may also have triggered large-scale star-formation activity in NGC 4141, resulting in the formation of the stellar progenitor of FRB 20250316A and the other transients. Our highest-resolution (480 pc) GMRT H i 21 cm image finds no H i 21 cm emission from the location of FRB 20250316A or the nearby star-forming region, suggesting that most of the H i here has been either ionized or converted into the molecular phase. Our nondetection of continuum emission at the location of FRB 20250316A yields the 3σ upper limit νL1.38 GHz < 4.4 × 1034 erg s−1 on the 1.38 GHz radio luminosity of a putative persistent radio source associated with FRB 20250316A, one of the strongest constraints on the radio luminosity of such an associated persistent radio source.
我们报道了巨型米波射电望远镜（GMRT）在z = 0.0063处对FRB 20250316A的宿主星系NGC 4141的21厘米成像。我们的GMRT H i 21 cm图像的空间分辨率为z≈0.0063,≈0.48-8.0 kpc，并提供了以下证据：(i)西南方向的伴星LEDA 2582852， （ii）西南方向附近（27 kpc远）的H i云，（iii） NGC 4141和LEDA 2582852的H i分布受到干扰，以及（iv） NGC 4141西南边缘的高H i柱密度。斯隆数字巡天（Sloan Digital Sky Survey）的光谱显示，NGC 4141西南盘的金属丰度较低，而恒星形成率（SFR）表面密度较高，基于h α的SFR估计明显高于星系演化探测器近紫外图像的相同位置，表明最近发生了恒星形成爆发。NGC 4141的总SFR通过Hα谱线也比1.4 GHz射电连续谱线更高。上述证据表明，NGC 4141最近（在最后≈3 Myr内）通过合并或吸积获得了金属贫气体，这导致了西南星暴，也可能引发了NGC 4141的大规模恒星形成活动，导致FRB 20250316A的恒星祖先和其他瞬变的形成。我们的最高分辨率（480 pc） GMRT H i 21 cm图像在FRB 20250316A的位置或附近的恒星形成区没有发现H i 21 cm的辐射，这表明这里的大部分H要么被电离，要么被转化为分子相。我们在FRB 20250316A的位置未探测到连续辐射，这使得与FRB 20250316A相关的假定持续射电源的1.38 GHz射电亮度的3σ上限νL1.38 GHz < 4.4 × 1034 erg s−1，这是对此类相关持续射电源的射电亮度的最强限制之一。
{"title":"High-resolution Giant Metrewave Radio Telescope H i 21 cm Imaging of the Host Galaxy of FRB 20250316A","authors":"Balpreet Kaur, Nissim Kanekar and J. Xavier Prochaska","doi":"10.3847/1538-4357/ae4d4a","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4d4a","url":null,"abstract":"We report Giant Metrewave Radio Telescope (GMRT) H i 21 cm imaging of NGC 4141, the host galaxy of FRB 20250316A at z = 0.0063. Our GMRT H i 21 cm images have spatial resolutions, at z ≈ 0.0063, of ≈0.48–8.0 kpc, and provide evidence for (i) a companion galaxy, LEDA 2582852, to the southwest, (ii) a nearby (27 kpc distant) H i cloud to the southwest, (iii) disturbances in the H i distributions of both NGC 4141 and LEDA 2582852, and (iv) high H i column densities in the southwestern outskirts of NGC 4141. A Sloan Digital Sky Survey spectrum yields a low metallicity and a high star formation rate (SFR) surface density in the southwestern disk of NGC 4141, and an Hα-based SFR estimate that is significantly higher than that at the same location from the Galaxy Evolution Explorer near-ultraviolet image, indicating a recent burst of star formation. The total SFR of NGC 4141 is also found to be higher via the Hα line than from the 1.4 GHz radio continuum. The above evidence indicates that NGC 4141 has recently (within the last ≈3 Myr) acquired metal-poor gas, via either a merger or accretion, that resulted in the southwestern starburst and that may also have triggered large-scale star-formation activity in NGC 4141, resulting in the formation of the stellar progenitor of FRB 20250316A and the other transients. Our highest-resolution (480 pc) GMRT H i 21 cm image finds no H i 21 cm emission from the location of FRB 20250316A or the nearby star-forming region, suggesting that most of the H i here has been either ionized or converted into the molecular phase. Our nondetection of continuum emission at the location of FRB 20250316A yields the 3σ upper limit νL1.38 GHz < 4.4 × 1034 erg s−1 on the 1.38 GHz radio luminosity of a putative persistent radio source associated with FRB 20250316A, one of the strongest constraints on the radio luminosity of such an associated persistent radio source.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147664166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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