Pub Date : 2024-11-19DOI: 10.3847/1538-4357/ad834f
Tian-Ye Xia, Juntai Shen, Zhi Li, Huai-jin Feng, Loránt O. Sjouwerman, Ylva M. Pihlström, Megan O. Lewis and Michael C. Stroh
We introduce a novel method that utilizes the longitude–velocity (l − v) envelope to constrain the Milky Way (MW) bar potential. Previous work used the l − v diagram to explain the distribution of the observed high-velocity stars. We successfully reproduce their results but find that their method is limited to only one type of periodic orbits. In contrast, we propose that the l − v envelope provides much more comprehensive constraints. We compare the properties of test particles in the M. Portail et al. MW potential model (P17) with the observed SiO maser stars from the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey. We find that the l − v envelope generated by the bar potential demonstrates reasonable agreement with the observational data, albeit with slight discrepancies near the Galactic center. The inconsistencies suggest that the P17 potential yields a lower central rotation curve, a slightly larger quadrupole strength, or a possibly underestimated pattern speed. We also adopt an updated version of the P17 potential with a modified central mass component proposed by G. H. Hunter et al. (H24). The fitting of the l − v envelope suggests that the H24 potential does not completely address the existing challenges and may hint at a possible underestimation of the central bar mass. Our study demonstrates that the l − v envelope can be used as a valuable tool for constraining the Galactic potential and provides insights into the MW bar potential.
我们介绍了一种利用经度-速度（l - v）包络来约束银河（MW）棒势的新方法。之前的工作使用 l - v 图来解释观测到的高速恒星的分布。我们成功地再现了他们的结果，但发现他们的方法仅限于一种类型的周期轨道。相比之下，我们提出l - v包络线提供的约束要全面得多。我们将波特尔等人的 MW 势模型（P17）中测试粒子的性质与 Bulge 不对称和动态演化（BAaDE）巡天观测到的 SiO maser 恒星进行了比较。我们发现，棒状势产生的 l - v 包络与观测数据显示出合理的一致性，尽管在银河系中心附近略有出入。这些不一致表明 P17 势产生的中心旋转曲线较低，四极强度稍大，或者可能低估了模式速度。我们还采用了由 G. H. Hunter 等人提出的带有修改过的中心质量分量的更新版 P17 势（H24）。l - v包络线的拟合结果表明，H24势能并不能完全解决现有的难题，而且可能暗示了对中心棒质量的低估。我们的研究表明，l - v包络线可以作为约束银河系势能的重要工具，并为了解MW棒状势能提供了启示。
{"title":"The Milky Way Bar Potential Constrained by the Kinematics of SiO Maser Stars in BAaDE Survey","authors":"Tian-Ye Xia, Juntai Shen, Zhi Li, Huai-jin Feng, Loránt O. Sjouwerman, Ylva M. Pihlström, Megan O. Lewis and Michael C. Stroh","doi":"10.3847/1538-4357/ad834f","DOIUrl":"https://doi.org/10.3847/1538-4357/ad834f","url":null,"abstract":"We introduce a novel method that utilizes the longitude–velocity (l − v) envelope to constrain the Milky Way (MW) bar potential. Previous work used the l − v diagram to explain the distribution of the observed high-velocity stars. We successfully reproduce their results but find that their method is limited to only one type of periodic orbits. In contrast, we propose that the l − v envelope provides much more comprehensive constraints. We compare the properties of test particles in the M. Portail et al. MW potential model (P17) with the observed SiO maser stars from the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey. We find that the l − v envelope generated by the bar potential demonstrates reasonable agreement with the observational data, albeit with slight discrepancies near the Galactic center. The inconsistencies suggest that the P17 potential yields a lower central rotation curve, a slightly larger quadrupole strength, or a possibly underestimated pattern speed. We also adopt an updated version of the P17 potential with a modified central mass component proposed by G. H. Hunter et al. (H24). The fitting of the l − v envelope suggests that the H24 potential does not completely address the existing challenges and may hint at a possible underestimation of the central bar mass. Our study demonstrates that the l − v envelope can be used as a valuable tool for constraining the Galactic potential and provides insights into the MW bar potential.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670919","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 : 2024-11-19DOI: 10.3847/1538-4357/ad84f9
Liping Yang, Zhike Xue, Jincheng Wang, Liheng Yang, Qiaoling Li, Yian Zhou, Yang Peng and Xinsheng Zhang
Although numerous works have concentrated on minifilament eruption in complex configurations, the detailed triggering mechanism is still an open question. Using the observational data from the New Vacuum Solar Telescope and Solar Dynamics Observatory, we studied a two-step magnetic reconnection process that triggered a minifilament that erupted intermittently within a fan-spine structure in the active region NOAA 13272. The first-step reconnection occurred between a set of low-lying small-scale magnetic loops and their nearby inner spine, resulting in the appearance of a brightening at the reconnection site and the reconfiguration of the inner spine. As the reconfigured inner spine approached the outer spine, reconnection occurred between them at the null point and led to the minifilament erupting partially. Subsequently, this two-step reconnection scenario occurred again and triggered the minifilament to erupt completely. The null point reconnection was supported by the changes in the topological structure of the inner spine and the outer spine, circular ribbon flares, remote brightenings, and the brightening of the outer spine. The null point reconnection related to the second eruption was also confirmed by some plasmoids expelled from the reconnection site. Further, the results of the magnetic field extrapolation reveal the existence of a fan-spine structure involving a three-dimensional null point. We suggest that the two-step reconnection triggers the two eruptions, in which the null point reconnection plays a direct role, but the dynamical evolution of the inner spine and the outer spine driven by the first-step reconnection might be a precursor of the subsequent null point reconnection.
{"title":"Two Intermittent Eruptions of a Minifilament Triggered by a Two-step Magnetic Reconnection Within a Fan-spine Configuration","authors":"Liping Yang, Zhike Xue, Jincheng Wang, Liheng Yang, Qiaoling Li, Yian Zhou, Yang Peng and Xinsheng Zhang","doi":"10.3847/1538-4357/ad84f9","DOIUrl":"https://doi.org/10.3847/1538-4357/ad84f9","url":null,"abstract":"Although numerous works have concentrated on minifilament eruption in complex configurations, the detailed triggering mechanism is still an open question. Using the observational data from the New Vacuum Solar Telescope and Solar Dynamics Observatory, we studied a two-step magnetic reconnection process that triggered a minifilament that erupted intermittently within a fan-spine structure in the active region NOAA 13272. The first-step reconnection occurred between a set of low-lying small-scale magnetic loops and their nearby inner spine, resulting in the appearance of a brightening at the reconnection site and the reconfiguration of the inner spine. As the reconfigured inner spine approached the outer spine, reconnection occurred between them at the null point and led to the minifilament erupting partially. Subsequently, this two-step reconnection scenario occurred again and triggered the minifilament to erupt completely. The null point reconnection was supported by the changes in the topological structure of the inner spine and the outer spine, circular ribbon flares, remote brightenings, and the brightening of the outer spine. The null point reconnection related to the second eruption was also confirmed by some plasmoids expelled from the reconnection site. Further, the results of the magnetic field extrapolation reveal the existence of a fan-spine structure involving a three-dimensional null point. We suggest that the two-step reconnection triggers the two eruptions, in which the null point reconnection plays a direct role, but the dynamical evolution of the inner spine and the outer spine driven by the first-step reconnection might be a precursor of the subsequent null point reconnection.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670964","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 : 2024-11-19DOI: 10.3847/1538-4357/ad8088
Indrani Pal, Anju A., H. Sreehari, Gitika Rameshan, C. S. Stalin, Claudio Ricci and S. Marchesi
We carried out a uniform and systematic analysis of a sample of 112 nearby bright Seyfert 1 type active galactic nuclei, the observations of which were carried out by the Nuclear Spectroscopic Telescope Array between 2013 August and 2022 May. The main goal of this analysis is to investigate the nature of the X-ray corona in Seyfert 1 galaxies. By fitting a physical model to the NuSTAR spectra, we could constrain the high-energy cutoff (Ecut) for 73 sources in our sample. To estimate the temperature of the corona (kTe) in our sample of 112 sources, we used the Comptonization model to fit their spectra. We could constrain kTe in 42 sources. We found a strong positive correlation between Ecut and kTe, with most of the sources lying above the empirical approximation of Ecut = 2−3 kTe. We investigated for possible correlations between various properties of the corona obtained from physical model fits to the observed spectra and between various coronal parameters and physical properties of the sources such as Eddington ratio and black hole mass. We found (a) a strong correlation between Ecut and the photon index and (b) a significant negative correlation between kTe and the optical depth. From detailed statistical analysis of the correlation of coronal parameters with the Eddington ratio and black hole mass, we found no significant correlation. The correlations observed in this study indicate that an optically thin corona is needed to sustain a hotter corona with a steeper spectrum.
{"title":"On the Properties of X-Ray Corona in Seyfert 1 Galaxies","authors":"Indrani Pal, Anju A., H. Sreehari, Gitika Rameshan, C. S. Stalin, Claudio Ricci and S. Marchesi","doi":"10.3847/1538-4357/ad8088","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8088","url":null,"abstract":"We carried out a uniform and systematic analysis of a sample of 112 nearby bright Seyfert 1 type active galactic nuclei, the observations of which were carried out by the Nuclear Spectroscopic Telescope Array between 2013 August and 2022 May. The main goal of this analysis is to investigate the nature of the X-ray corona in Seyfert 1 galaxies. By fitting a physical model to the NuSTAR spectra, we could constrain the high-energy cutoff (Ecut) for 73 sources in our sample. To estimate the temperature of the corona (kTe) in our sample of 112 sources, we used the Comptonization model to fit their spectra. We could constrain kTe in 42 sources. We found a strong positive correlation between Ecut and kTe, with most of the sources lying above the empirical approximation of Ecut = 2−3 kTe. We investigated for possible correlations between various properties of the corona obtained from physical model fits to the observed spectra and between various coronal parameters and physical properties of the sources such as Eddington ratio and black hole mass. We found (a) a strong correlation between Ecut and the photon index and (b) a significant negative correlation between kTe and the optical depth. From detailed statistical analysis of the correlation of coronal parameters with the Eddington ratio and black hole mass, we found no significant correlation. The correlations observed in this study indicate that an optically thin corona is needed to sustain a hotter corona with a steeper spectrum.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"250 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670915","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 : 2024-11-19DOI: 10.3847/1538-4357/ad8135
Ravi Pratap Dubey, Christian Fendt and Bhargav Vaidya
Relativistic magnetized jets, originating near black holes, are observed to exhibit substructured flows. In this study, we present synthetic synchrotron-emission signatures for different lines of sight and frequencies, derived from three-dimensional relativistic magnetohydrodynamic simulations of pc-scale Active Galactic Nuclei jets. These simulations apply different injection nozzles, injecting steady, variable, and precessing jets. Extending our previous study, here, we have developed a bridge to connect jet dynamics and particle acceleration within relativistic shocks with nonthermal radiation dominant in jets. The emission is derived from Lagrangian particles—injected into the jet and following the fluid—accelerated through diffusive shock acceleration and subsequently cooled by emitting energy via synchrotron and inverse-Compton processes. Overall, the different shock structures lead to the formation of numerous localized emission patterns—interpreted as jet knots. These knot patterns can fade or flare, also as a consequence of merging or Doppler boosting, leading to jet variability. We find knots with high-enough pattern speed supposed to be visible as superluminal motion ≲5c. Synchrotron spectra of all jets reveal double-humped structures, reflecting multiple electron populations characterized by the nature of underlying shock and their age. The precessing jet is the most powerful emitter, featuring a spectrum flatter than the steady and the variable jet. The emission, although essentially governed by the acceleration through shocks, depends on the cooling history of the particle as well. Overall, the continuous reacceleration of electrons through shocks along the jet we found is an essential prerequisite for observing extended jet emission over large timescales and length scales.
据观测，源自黑洞附近的相对论磁化喷流表现出亚结构流。在这项研究中，我们展示了不同视线和频率下的合成同步辐射特征，这些特征来自于对 pc 级活动星系核喷流的三维相对论磁流体动力学模拟。这些模拟应用了不同的喷射喷嘴，喷射稳定、可变和前冲射流。在此，我们扩展了之前的研究，开发了一座桥梁，将相对论冲击内的喷流动力学和粒子加速与喷流中占主导地位的非热辐射联系起来。这种辐射来自拉格朗日粒子--它们被注入喷流并跟随流体--通过扩散冲击加速，随后通过同步辐射和反康普顿过程发射能量冷却。总之，不同的冲击结构会形成许多局部发射模式--被解释为喷流节。这些喷流结图案可能会消退或耀斑，也可能是合并或多普勒增强的结果，从而导致喷流变异。我们发现的节具有足够高的模式速度，可以被认为是可见的超光速运动≲5c。所有喷流的同步辐射光谱都显示了双驼峰结构，反映了多个电子群，其特征与底层冲击的性质及其年龄有关。前冲喷流是最强大的发射体，其光谱比稳定喷流和可变喷流更平坦。这种发射虽然主要受冲击加速度的影响，但也取决于粒子的冷却历史。总之，我们发现电子通过沿射流的冲击持续再加速是观测大时间尺度和长度尺度的扩展射流发射的必要先决条件。
{"title":"Particles in Relativistic Magnetohydrodynamic Jets. II. Bridging Jet Dynamics with Multi–wave band Nonthermal Emission Signatures","authors":"Ravi Pratap Dubey, Christian Fendt and Bhargav Vaidya","doi":"10.3847/1538-4357/ad8135","DOIUrl":"https://doi.org/10.3847/1538-4357/ad8135","url":null,"abstract":"Relativistic magnetized jets, originating near black holes, are observed to exhibit substructured flows. In this study, we present synthetic synchrotron-emission signatures for different lines of sight and frequencies, derived from three-dimensional relativistic magnetohydrodynamic simulations of pc-scale Active Galactic Nuclei jets. These simulations apply different injection nozzles, injecting steady, variable, and precessing jets. Extending our previous study, here, we have developed a bridge to connect jet dynamics and particle acceleration within relativistic shocks with nonthermal radiation dominant in jets. The emission is derived from Lagrangian particles—injected into the jet and following the fluid—accelerated through diffusive shock acceleration and subsequently cooled by emitting energy via synchrotron and inverse-Compton processes. Overall, the different shock structures lead to the formation of numerous localized emission patterns—interpreted as jet knots. These knot patterns can fade or flare, also as a consequence of merging or Doppler boosting, leading to jet variability. We find knots with high-enough pattern speed supposed to be visible as superluminal motion ≲5c. Synchrotron spectra of all jets reveal double-humped structures, reflecting multiple electron populations characterized by the nature of underlying shock and their age. The precessing jet is the most powerful emitter, featuring a spectrum flatter than the steady and the variable jet. The emission, although essentially governed by the acceleration through shocks, depends on the cooling history of the particle as well. Overall, the continuous reacceleration of electrons through shocks along the jet we found is an essential prerequisite for observing extended jet emission over large timescales and length scales.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"54 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670917","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 : 2024-11-19DOI: 10.3847/1538-4357/ad7de3
Wun-Yi Chen, Ke-Jung Chen and Masaomi Ono
Shock breakout is the first electromagnetic signal from supernovae (SNe), which contains important information on the explosion energy and the size and chemical composition of the progenitor star. This paper presents the first two-dimensional (2D) multiwavelength radiation hydrodynamics simulations of SN 1987A shock breakout by using the CASTRO code with the OPAL opacity table considering eight photon groups from infrared to X-ray. To investigate the impact of the pre-SN environment of SN 1987A, we consider three possible circumstellar medium environments: a steady wind, an eruptive mass loss, and the existence of a companion star. In sum, the resulting breakout light curve has an hour-long duration and a peak luminosity of ∼4 × 1046 erg s−1, with a decay rate of ∼3.5 mag hr−1 in X-ray. The dominant band transits to UV around 3 hr after the initial breakout, and its luminosity has a decay rate of ∼1.5 mag hr−1 that agrees well with the observed shock breakout tail. The detailed features of breakout emission are sensitive to the pre-explosion environment. Furthermore, our 2D simulations demonstrate the importance of multidimensional mixing and its impacts on shock dynamics and radiation emission. The mixing emerging from the shock breakout may lead to a global asymmetry of SN ejecta and affect its later SN remnant formation.
{"title":"Multidimensional Radiation Hydrodynamics Simulations of SN 1987A Shock Breakout","authors":"Wun-Yi Chen, Ke-Jung Chen and Masaomi Ono","doi":"10.3847/1538-4357/ad7de3","DOIUrl":"https://doi.org/10.3847/1538-4357/ad7de3","url":null,"abstract":"Shock breakout is the first electromagnetic signal from supernovae (SNe), which contains important information on the explosion energy and the size and chemical composition of the progenitor star. This paper presents the first two-dimensional (2D) multiwavelength radiation hydrodynamics simulations of SN 1987A shock breakout by using the CASTRO code with the OPAL opacity table considering eight photon groups from infrared to X-ray. To investigate the impact of the pre-SN environment of SN 1987A, we consider three possible circumstellar medium environments: a steady wind, an eruptive mass loss, and the existence of a companion star. In sum, the resulting breakout light curve has an hour-long duration and a peak luminosity of ∼4 × 1046 erg s−1, with a decay rate of ∼3.5 mag hr−1 in X-ray. The dominant band transits to UV around 3 hr after the initial breakout, and its luminosity has a decay rate of ∼1.5 mag hr−1 that agrees well with the observed shock breakout tail. The detailed features of breakout emission are sensitive to the pre-explosion environment. Furthermore, our 2D simulations demonstrate the importance of multidimensional mixing and its impacts on shock dynamics and radiation emission. The mixing emerging from the shock breakout may lead to a global asymmetry of SN ejecta and affect its later SN remnant formation.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670914","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 : 2024-11-19DOI: 10.3847/1538-4357/ad7b0f
Antonio J. Porras-Valverde, John C. Forbes, Rachel S. Somerville, Adam R. H. Stevens, Kelly Holley-Bockelmann, Andreas A. Berlind and Shy Genel
Semianalytic models (SAMs) systematically predict higher-stellar mass scatter at a given halo mass than hydrodynamical simulations and most empirical models. Our goal is to investigate the physical origin of this scatter by exploring modifications to the physics in the SAM Dark Sage. We design two black hole formation models that approximate results from the IllustrisTNG 300-1 hydrodynamical simulation. In the first model, we assign a fixed black hole mass of 106M⊙ to every halo that reaches 1010.5M⊙. In the second model, we disregard any black hole growth as implemented in the standard Dark Sage model. Instead, we force all black hole masses to follow the median z = 0 black hole mass–halo mass relation in IllustrisTNG 300-1 with an imposed fixed scatter. We find that each model on its own does not significantly reduce the scatter in stellar mass. To explore the effects of active galactic nucleus (AGN) feedback in addition to black hole seeding, we replace the native Dark Sage AGN feedback model with a simple model where we turn off cooling for galaxies with black hole masses above 108M⊙. With the additional modification in AGN feedback, we find that the supermassive black hole seeding and fixed conditional distribution models create a significant reduction in the scatter in stellar mass at halo masses between 1011–14M⊙. These results suggest that AGN feedback in SAMs acts in a qualitatively different way than feedback implemented in cosmological simulations. Either or both may require substantial modification to match the empirically inferred scatter in the stellar mass–halo mass relation.
{"title":"Why Do Semianalytic Models Predict Higher Scatter in the Stellar Mass–Halo Mass Relation Than Cosmological Hydrodynamic Simulations?","authors":"Antonio J. Porras-Valverde, John C. Forbes, Rachel S. Somerville, Adam R. H. Stevens, Kelly Holley-Bockelmann, Andreas A. Berlind and Shy Genel","doi":"10.3847/1538-4357/ad7b0f","DOIUrl":"https://doi.org/10.3847/1538-4357/ad7b0f","url":null,"abstract":"Semianalytic models (SAMs) systematically predict higher-stellar mass scatter at a given halo mass than hydrodynamical simulations and most empirical models. Our goal is to investigate the physical origin of this scatter by exploring modifications to the physics in the SAM Dark Sage. We design two black hole formation models that approximate results from the IllustrisTNG 300-1 hydrodynamical simulation. In the first model, we assign a fixed black hole mass of 106M⊙ to every halo that reaches 1010.5M⊙. In the second model, we disregard any black hole growth as implemented in the standard Dark Sage model. Instead, we force all black hole masses to follow the median z = 0 black hole mass–halo mass relation in IllustrisTNG 300-1 with an imposed fixed scatter. We find that each model on its own does not significantly reduce the scatter in stellar mass. To explore the effects of active galactic nucleus (AGN) feedback in addition to black hole seeding, we replace the native Dark Sage AGN feedback model with a simple model where we turn off cooling for galaxies with black hole masses above 108M⊙. With the additional modification in AGN feedback, we find that the supermassive black hole seeding and fixed conditional distribution models create a significant reduction in the scatter in stellar mass at halo masses between 1011–14M⊙. These results suggest that AGN feedback in SAMs acts in a qualitatively different way than feedback implemented in cosmological simulations. Either or both may require substantial modification to match the empirically inferred scatter in the stellar mass–halo mass relation.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679008","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 : 2024-11-19DOI: 10.3847/1538-4357/ad7b0a
Nishant Mishra, Sean D. Johnson, Gwen C. Rudie, Hsiao-Wen Chen, Joop Schaye, Zhijie Qu, Fakhri S. Zahedy, Erin T. Boettcher, Sebastiano Cantalupo, Mandy C. Chen, Claude-André Faucher-Giguére, Jenny E. Greene, Jennifer I-Hsiu Li, Zhuoqi (Will) Liu, Sebastian Lopez and Patrick Petitjean
The shallow potential wells of star-forming dwarf galaxies make their surrounding circumgalactic and intergalactic medium (CGM/IGM) sensitive laboratories for studying the inflows and outflows thought to regulate galaxy evolution. We present new absorption-line measurements in quasar sight lines, probing within projected distances of <300 kpc from 91 star-forming field dwarf galaxies with a median stellar mass of at 0.077 < z < 0.73, from the Cosmic Ultraviolet Baryon Survey (CUBS). In this redshift range, the CUBS quasar spectra cover a suite of transitions including H i, low, and intermediate metal ions (e.g., C ii, Si ii, C iii, and Si iii), and highly ionized O vi. This CUBS-Dwarfs survey enables constraints with samples nine times larger than past dwarf CGM/IGM studies with similar ionic coverage. We find that low and intermediate ionization metal absorption is rare around dwarf galaxies, consistent with previous surveys of local dwarfs. In contrast, highly ionized O vi is commonly observed in sight lines that pass within the virial radius of a dwarf, and O vi detection rates are nonnegligible at projected distances of 1−2× the virial radius. Based on these measurements, we estimate that the O vi-bearing phase of the CGM/IGM accounts for a dominant share of the metal budget of dwarf galaxies. The absorption kinematics suggest that a relatively modest fraction of the O vi-bearing gas is formally unbound. Together, these results imply that low-mass systems at z ≲ 1 effectively retain a substantial fraction of their metals within the nearby CGM and IGM.
恒星形成矮星系的浅势阱使其周围的星系周和星系际介质（CGM/IGM）成为研究被认为调节星系演化的流入和流出的敏感实验室。我们展示了类星体视线中新的吸收线测量结果，探测了宇宙紫外线重子巡天（CUBS）中恒星质量中位数为0.077 < z < 0.73的91个恒星形成场矮星系小于300 kpc的投影距离。在这个红移范围内，CUBS 类星体光谱涵盖了一整套跃迁，包括 H i、低级和中级金属离子（如 C ii、Si ii、C iii 和 Si iii）以及高度电离的 O vi。这次 CUBS-Dwarfs 勘测所获得的样本比以往类似离子覆盖范围的矮CGM/IGM 研究大九倍，从而能够进行约束。我们发现，矮星系周围很少有低电离和中电离金属吸收，这与以前的局地矮星系调查一致。与此相反，在通过矮星系半径范围内的视线中，通常可以观测到高度电离的 O vi，而且在投影距离为半径的 1-2 倍时，O vi 的探测率是不可忽略的。根据这些测量结果，我们估计在矮星系的金属预算中，CGM/IGM 的含 O vi 阶段占主要份额。吸收运动学表明，含 O vi 气体中相对较小的一部分是形式上未被束缚的。这些结果共同表明，z≲1的低质量星系将其金属的很大一部分有效地保留在附近的CGM和IGM中。
{"title":"The Cosmic Ultraviolet Baryon Survey (CUBS). IX. The Enriched Circumgalactic and Intergalactic Medium Around Star-forming Field Dwarf Galaxies Traced by O vi Absorption","authors":"Nishant Mishra, Sean D. Johnson, Gwen C. Rudie, Hsiao-Wen Chen, Joop Schaye, Zhijie Qu, Fakhri S. Zahedy, Erin T. Boettcher, Sebastiano Cantalupo, Mandy C. Chen, Claude-André Faucher-Giguére, Jenny E. Greene, Jennifer I-Hsiu Li, Zhuoqi (Will) Liu, Sebastian Lopez and Patrick Petitjean","doi":"10.3847/1538-4357/ad7b0a","DOIUrl":"https://doi.org/10.3847/1538-4357/ad7b0a","url":null,"abstract":"The shallow potential wells of star-forming dwarf galaxies make their surrounding circumgalactic and intergalactic medium (CGM/IGM) sensitive laboratories for studying the inflows and outflows thought to regulate galaxy evolution. We present new absorption-line measurements in quasar sight lines, probing within projected distances of <300 kpc from 91 star-forming field dwarf galaxies with a median stellar mass of at 0.077 < z < 0.73, from the Cosmic Ultraviolet Baryon Survey (CUBS). In this redshift range, the CUBS quasar spectra cover a suite of transitions including H i, low, and intermediate metal ions (e.g., C ii, Si ii, C iii, and Si iii), and highly ionized O vi. This CUBS-Dwarfs survey enables constraints with samples nine times larger than past dwarf CGM/IGM studies with similar ionic coverage. We find that low and intermediate ionization metal absorption is rare around dwarf galaxies, consistent with previous surveys of local dwarfs. In contrast, highly ionized O vi is commonly observed in sight lines that pass within the virial radius of a dwarf, and O vi detection rates are nonnegligible at projected distances of 1−2× the virial radius. Based on these measurements, we estimate that the O vi-bearing phase of the CGM/IGM accounts for a dominant share of the metal budget of dwarf galaxies. The absorption kinematics suggest that a relatively modest fraction of the O vi-bearing gas is formally unbound. Together, these results imply that low-mass systems at z ≲ 1 effectively retain a substantial fraction of their metals within the nearby CGM and IGM.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670913","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 : 2024-11-19DOI: 10.3847/1538-4357/ad83b8
Behzad Bojnordi Arbab, Wouter Vlemmings, Theo Khouri and Susanne Höfner
We investigate the observable characteristics of the extended atmospheres of asymptotic giant branch (AGB) stars across a wide range of radio and (sub-)millimeter wavelengths using state-of-the-art 1D dynamical atmosphere and wind models over one pulsation period. We also study the relationships between the observable features and model properties. We further study practical distance ranges for observable sources assuming the capabilities of current and upcoming observatories. We present time-variable, frequency-dependent profiles of pulsating AGB stars’ atmospheres, illustrating observable features in resolved and unresolved observations, including disk brightness temperature, photosphere radius, and resolved and unresolved spectral indices. Notably, temporal variations in disk brightness temperature closely mirror the temperature variability of the stellar atmosphere. We find that while the photospheric radius decreases due to gas dilution in the layers between consecutive shocks, the increase in the observed stellar radius reflects shock propagation through the atmosphere during the expansion phase, providing a direct measurement method for the shock velocity. Furthermore, our models indicate that enhanced gas temperatures after the passage of a strong shock might be observable in the high-frequency Atacama Large Millimeter/submillimeter Array (ALMA) bands as a decrease in the brightness temperature with increasing frequency. We demonstrate that synthetic observations based on state-of-the-art dynamical atmosphere and wind models are necessary for proper interpretations of current (ALMA and Very Large Array (VLA)) and future (Square Kilometre Array and next-generation VLA) observations and that multiwavelength observations of AGB stars are crucial for empirical studies of their extended atmospheres.
{"title":"Probing the Extended Atmospheres of AGB Stars. I. Synthetic Imaging of 1D Hydrodynamical Models at Radio and (Sub-)millimeter Wavelengths","authors":"Behzad Bojnordi Arbab, Wouter Vlemmings, Theo Khouri and Susanne Höfner","doi":"10.3847/1538-4357/ad83b8","DOIUrl":"https://doi.org/10.3847/1538-4357/ad83b8","url":null,"abstract":"We investigate the observable characteristics of the extended atmospheres of asymptotic giant branch (AGB) stars across a wide range of radio and (sub-)millimeter wavelengths using state-of-the-art 1D dynamical atmosphere and wind models over one pulsation period. We also study the relationships between the observable features and model properties. We further study practical distance ranges for observable sources assuming the capabilities of current and upcoming observatories. We present time-variable, frequency-dependent profiles of pulsating AGB stars’ atmospheres, illustrating observable features in resolved and unresolved observations, including disk brightness temperature, photosphere radius, and resolved and unresolved spectral indices. Notably, temporal variations in disk brightness temperature closely mirror the temperature variability of the stellar atmosphere. We find that while the photospheric radius decreases due to gas dilution in the layers between consecutive shocks, the increase in the observed stellar radius reflects shock propagation through the atmosphere during the expansion phase, providing a direct measurement method for the shock velocity. Furthermore, our models indicate that enhanced gas temperatures after the passage of a strong shock might be observable in the high-frequency Atacama Large Millimeter/submillimeter Array (ALMA) bands as a decrease in the brightness temperature with increasing frequency. We demonstrate that synthetic observations based on state-of-the-art dynamical atmosphere and wind models are necessary for proper interpretations of current (ALMA and Very Large Array (VLA)) and future (Square Kilometre Array and next-generation VLA) observations and that multiwavelength observations of AGB stars are crucial for empirical studies of their extended atmospheres.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670920","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 : 2024-11-19DOI: 10.3847/1538-4357/ad83b9
Robin H. D. Corbet, Ralf Ballhausen, Peter A. Becker, Joel B. Coley, Felix Fuerst, Keith C. Gendreau, Sebastien Guillot, Nazma Islam, Gaurava Kumar Jaisawal, Peter Jenke, Peter Kretschmar, Alexander Lange, Christian Malacaria, Mason Ng, Katja Pottschmidt, Pragati Pradhan, Paul S. Ray, Richard E. Rothschild, Philipp Thalhammer, Lee J. Townsend, Joern Wilms, Colleen A. Wilson-Hodge and Michael T. Wolff
XTE J1829−098 is a transient X-ray pulsar with a period of ∼7.8 s. It is a candidate Be star system, although the evidence for this is not yet definitive. We investigated the twenty-year-long X-ray light curve using the Rossi X-ray Timing Explorer Proportional Counter Array (PCA), Neil Gehrels Swift Observatory Burst Alert Telescope, and the Monitor of All-sky X-ray Image. We find that all three light curves are clearly modulated on the ∼244 days orbital period previously reported from PCA monitoring observations, with outbursts confined to a narrow phase range. The light curves also show that XTE J1829−098 was in an inactive state between approximately 2008 December and 2018 April, and no strong outbursts occurred. Such behavior is typical of Be X-ray binary systems, with the absence of outbursts likely related to the dissipation of the Be star's decretion disk. The mean outburst shapes can be approximated with a triangular profile and, from a joint fit of this to all three light curves, we refine the orbital period to 243.95 ± 0.04 days. The mean outburst profile does not show any asymmetry and has a total phase duration of 0.140 ± 0.007. However, the PCA light curve shows that there is considerable cycle-to-cycle variability of the individual outbursts. We compare the properties of XTE J1829−098 with other sources that show short phase-duration outbursts, in particular GS 1843−02 (2S 1845−024), which has a very similar orbital period, but longer pulse period, and whose orbit is known to be highly eccentric.
XTE J1829-098是一颗周期为7.8秒的瞬态X射线脉冲星。我们利用罗西 X 射线定时探测器比例计数器阵列（PCA）、尼尔-盖尔斯-斯威夫特天文台爆发警报望远镜和全天空 X 射线图像监视器研究了长达二十年的 X 射线光变曲线。我们发现，这三个光曲线都明显地调制在先前根据 PCA 监测观测报告的 244 天轨道周期上，爆发仅限于一个狭窄的相位范围。光曲线还显示，XTE J1829-098 在大约 2008 年 12 月至 2018 年 4 月期间处于不活跃状态，没有发生强烈的爆发。这种行为是 Be X 射线双星系统的典型特征，没有爆发可能与 Be 星减弱盘的耗散有关。爆发的平均形状可以用一个三角形轮廓来近似，通过对所有三条光曲线的联合拟合，我们将轨道周期细化为 243.95 ± 0.04 天。平均爆发曲线没有显示出任何不对称性，总相位持续时间为 0.140 ± 0.007。不过，PCA 光曲线显示，单个爆发在周期与周期之间存在相当大的可变性。我们将 XTE J1829-098 的特性与其他显示短相位持续时间爆发的天体进行了比较，特别是 GS 1843-02 （2S 1845-024），它的轨道周期非常相似，但脉冲周期更长，而且其轨道已知高度偏心。
{"title":"Sharp Periodic Flares and Long-term Variability in the High-mass X-Ray Binary XTE J1829−098 from RXTE PCA, Swift BAT, and MAXI Observations","authors":"Robin H. D. Corbet, Ralf Ballhausen, Peter A. Becker, Joel B. Coley, Felix Fuerst, Keith C. Gendreau, Sebastien Guillot, Nazma Islam, Gaurava Kumar Jaisawal, Peter Jenke, Peter Kretschmar, Alexander Lange, Christian Malacaria, Mason Ng, Katja Pottschmidt, Pragati Pradhan, Paul S. Ray, Richard E. Rothschild, Philipp Thalhammer, Lee J. Townsend, Joern Wilms, Colleen A. Wilson-Hodge and Michael T. Wolff","doi":"10.3847/1538-4357/ad83b9","DOIUrl":"https://doi.org/10.3847/1538-4357/ad83b9","url":null,"abstract":"XTE J1829−098 is a transient X-ray pulsar with a period of ∼7.8 s. It is a candidate Be star system, although the evidence for this is not yet definitive. We investigated the twenty-year-long X-ray light curve using the Rossi X-ray Timing Explorer Proportional Counter Array (PCA), Neil Gehrels Swift Observatory Burst Alert Telescope, and the Monitor of All-sky X-ray Image. We find that all three light curves are clearly modulated on the ∼244 days orbital period previously reported from PCA monitoring observations, with outbursts confined to a narrow phase range. The light curves also show that XTE J1829−098 was in an inactive state between approximately 2008 December and 2018 April, and no strong outbursts occurred. Such behavior is typical of Be X-ray binary systems, with the absence of outbursts likely related to the dissipation of the Be star's decretion disk. The mean outburst shapes can be approximated with a triangular profile and, from a joint fit of this to all three light curves, we refine the orbital period to 243.95 ± 0.04 days. The mean outburst profile does not show any asymmetry and has a total phase duration of 0.140 ± 0.007. However, the PCA light curve shows that there is considerable cycle-to-cycle variability of the individual outbursts. We compare the properties of XTE J1829−098 with other sources that show short phase-duration outbursts, in particular GS 1843−02 (2S 1845−024), which has a very similar orbital period, but longer pulse period, and whose orbit is known to be highly eccentric.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"80 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670966","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 : 2024-11-18DOI: 10.3847/1538-4357/ad61e7
Marla Geha, Yao-Yuan Mao, Risa H. Wechsler, Yasmeen Asali, Erin Kado-Fong, Nitya Kallivayalil, Ethan O. Nadler, Erik J. Tollerud, Benjamin Weiner, Mithi A. C. de los Reyes, Yunchong Wang and John F. Wu
We present the star-forming properties of 378 satellite galaxies around 101 Milky Way analogs in the Satellites Around Galactic Analogs (SAGA) Survey, focusing on the environmental processes that suppress or quench star formation. In the SAGA stellar mass range of 106−10M⊙, we present quenched fractions, star-forming rates, gas-phase metallicities, and gas content. The fraction of SAGA satellites that are quenched increases with decreasing stellar mass and shows significant system-to-system scatter. SAGA satellite quenched fractions are highest in the central 100 kpc of their hosts and decline out to the virial radius. Splitting by specific star formation rate (sSFR), the least star-forming satellite quartile follows the radial trend of the quenched population. The median sSFR of star-forming satellites increases with decreasing stellar mass and is roughly constant with projected radius. Star-forming SAGA satellites are consistent with the star formation rate–stellar mass relationship determined in the Local Volume, while the median gas-phase metallicity is higher and median H i gas mass is lower at all stellar masses. We investigate the dependence of the satellite quenched fraction on host properties. Quenched fractions are higher in systems with larger host halo mass, but this trend is only seen in the inner 100 kpc; we do not see significant trends with host color or star formation rate. Our results suggest that lower-mass satellites and satellites inside 100 kpc are more efficiently quenched in a Milky Way–like environment, with these processes acting sufficiently slowly to preserve a population of star-forming satellites at all stellar masses and projected radii.
{"title":"The SAGA Survey. IV. The Star Formation Properties of 101 Satellite Systems around Milky Way–mass Galaxies","authors":"Marla Geha, Yao-Yuan Mao, Risa H. Wechsler, Yasmeen Asali, Erin Kado-Fong, Nitya Kallivayalil, Ethan O. Nadler, Erik J. Tollerud, Benjamin Weiner, Mithi A. C. de los Reyes, Yunchong Wang and John F. Wu","doi":"10.3847/1538-4357/ad61e7","DOIUrl":"https://doi.org/10.3847/1538-4357/ad61e7","url":null,"abstract":"We present the star-forming properties of 378 satellite galaxies around 101 Milky Way analogs in the Satellites Around Galactic Analogs (SAGA) Survey, focusing on the environmental processes that suppress or quench star formation. In the SAGA stellar mass range of 106−10M⊙, we present quenched fractions, star-forming rates, gas-phase metallicities, and gas content. The fraction of SAGA satellites that are quenched increases with decreasing stellar mass and shows significant system-to-system scatter. SAGA satellite quenched fractions are highest in the central 100 kpc of their hosts and decline out to the virial radius. Splitting by specific star formation rate (sSFR), the least star-forming satellite quartile follows the radial trend of the quenched population. The median sSFR of star-forming satellites increases with decreasing stellar mass and is roughly constant with projected radius. Star-forming SAGA satellites are consistent with the star formation rate–stellar mass relationship determined in the Local Volume, while the median gas-phase metallicity is higher and median H i gas mass is lower at all stellar masses. We investigate the dependence of the satellite quenched fraction on host properties. Quenched fractions are higher in systems with larger host halo mass, but this trend is only seen in the inner 100 kpc; we do not see significant trends with host color or star formation rate. Our results suggest that lower-mass satellites and satellites inside 100 kpc are more efficiently quenched in a Milky Way–like environment, with these processes acting sufficiently slowly to preserve a population of star-forming satellites at all stellar masses and projected radii.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670317","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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