The Astrophysical Journal最新文献

Evolution of Low Surface Brightness Ultrathin Galaxies: The Role of Dark Matter Halo and Bar Formation on Disk Thickness 低表面亮度超薄星系的演化：暗物质晕和棒状形成对星系盘厚度的作用

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/ae0991

K. Aditya and Arunima Banerjee

{"title":"Evolution of Low Surface Brightness Ultrathin Galaxies: The Role of Dark Matter Halo and Bar Formation on Disk Thickness","authors":"K. Aditya and Arunima Banerjee","doi":"10.3847/1538-4357/ae0991","DOIUrl":"https://doi.org/10.3847/1538-4357/ae0991","url":null,"abstract":"We investigate how stellar disks sustain their ultrathin structure throughout their evolution. We follow the evolution of ultrathin stellar disks with varying dark matter (DM) halo concentration (c) using collisionless N-body simulations with AREPO. We test models embedded in steep (c = 12), shallow (c = 2), and intermediate (c = 6) DM concentrations. Our models match the observed structural properties of the stellar disk in the low surface brightness (LSB) ultrathin galaxy FGC 2366, specifically its surface brightness, disk scalelength, and vertical thinness (hz/RD = 0.1), while excluding gas, allowing us to isolate the effects of DM. The internal disk heating mechanism driven by bars is suppressed in the LSB ultrathin stellar disks regardless of the DM concentration. The ratio of disk thickness (hz) to scalelength (RD) remains constant at ≤0.1 throughout their evolution. To clearly establish that the LSB nature of stellar disks is the key to preventing disk thickening, we construct the initial conditions by increasing the stellar mass fraction from fs ∼ 0.01 to 0.02 and 0.04, respectively, while keeping the total mass equal to 1011M⊙ and hz/RD ≤ 0.1 unchanged. We find that models with a higher stellar mass fraction embedded in a shallow DM potential (c = 2) form bars and undergo significant disk thickening (hz/RD ≫ 0.1) concurrent with the bar growth. We conclude that if the LSB disks are thin to begin with, they remain so throughout their evolution in isolation, regardless of the concentration of the DM halo.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282898","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}

引用次数: 0

Rotational Spectroscopy and Tentative Interstellar Detection of 3-hydroxypropanal (HOCH2CH2CHO) in the G+0.693-0.027 Molecular Cloud G+0.693-0.027分子云中3-羟基丙烷（HOCH2CH2CHO）的旋转光谱和星际探测

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/adfc62

Zachary T. P. Fried, Roman A. Motiyenko, Miguel Sanz-Novo, Lucie Kolesniková, Jean-Claude Guillemin, Laurent Margulès, Tereza Uhlíková, Arnaud Belloche, Jes K. Jørgensen, Martin S. Holdren, Ci Xue, Štěpán Urban, Izaskun Jiménez-Serra, Victor M. Rivilla and Brett A. McGuire

{"title":"Rotational Spectroscopy and Tentative Interstellar Detection of 3-hydroxypropanal (HOCH2CH2CHO) in the G+0.693-0.027 Molecular Cloud","authors":"Zachary T. P. Fried, Roman A. Motiyenko, Miguel Sanz-Novo, Lucie Kolesniková, Jean-Claude Guillemin, Laurent Margulès, Tereza Uhlíková, Arnaud Belloche, Jes K. Jørgensen, Martin S. Holdren, Ci Xue, Štěpán Urban, Izaskun Jiménez-Serra, Victor M. Rivilla and Brett A. McGuire","doi":"10.3847/1538-4357/adfc62","DOIUrl":"https://doi.org/10.3847/1538-4357/adfc62","url":null,"abstract":"We synthesized the astrochemically relevant molecule 3-hydroxypropanal (HOCH2CH2CHO) and subsequently measured and analyzed its rotational spectrum in several frequency regions ranging from 130 to 485 GHz. We analyzed the ground vibrational state as well as the two perturbed lowest-lying vibrationally excited states. With the resulting rotational parameters, we searched for this molecule in the Sagittarius B2(N) and NGC 6334I hot cores, the IRAS 16293-2422B hot corino, and the G+0.693-0.027 and TMC-1 molecular clouds. Rotational emission of 3-hydroxypropanal was tentatively detected toward G+0.693-0.027, and a column density of (8.6 ±1.4) × 1012 cm−2 was determined. However, this molecule was not detected in the other sources that were investigated. The chemical implications of this tentative discovery are analyzed, and several potential chemical formation pathways of this species are discussed.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"127 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282890","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}

引用次数: 0

A High-precision Dynamical Model of Callisto: Incorporating Rotation Effects within Multilayer Internal Structure Models 木卫四的高精度动力学模型：多层内部结构模型中包含旋转效应

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/adfe65

Kai Huang, Yongzhang Yang, Yuhao Chen, Yining Zhang and Yuqiang Li

{"title":"A High-precision Dynamical Model of Callisto: Incorporating Rotation Effects within Multilayer Internal Structure Models","authors":"Kai Huang, Yongzhang Yang, Yuhao Chen, Yining Zhang and Yuqiang Li","doi":"10.3847/1538-4357/adfe65","DOIUrl":"https://doi.org/10.3847/1538-4357/adfe65","url":null,"abstract":"China is planning to launch the “Tianwen-4” mission around the year 2030, with its aim being the exploration of Jupiter and its moon, Callisto. Within the realm of deep space exploration, the accuracy of ephemerides is of great importance. Current ephemerides employ a simplified rotation model for Callisto, which this study addresses by proposing a novel dynamical model. This model enhances the existing orbital dynamics by integrating Callisto’s rotational motions influenced by gravitational torques from the Sun, Jupiter, and other Galilean moons within an inertial frame, capturing the intricate coupling between Callisto’s orbital and rotational dynamics. The study establishes a full dynamical model by deriving analytical expressions for this coupling and developing an adjustment model for data fitting using precise orbit determination methods. Furthermore, the influence of tidal effects on Callisto’s motion is investigated, considering its multilayered internal structure. Results demonstrate that the difference between the newly established full model and the model in current ephemerides is on the order of tens of meters. When calculating the impact of different internal structures of Callisto on its orbit, the influence of three-layered and two-layered structures is on the order of meters, suggesting that the development of a high-precision dynamical model requires additional constraints on the internal structure of Callisto. This research provides a novel alternative for a new generation of precise numerical ephemerides for Callisto. Additionally, these findings provide a testing platform for the data from the “Tianwen-4” mission.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282893","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}

引用次数: 0

Estimation of Effective Viscosity to Quantify Collisional Behavior in Collisionless Plasma 估算有效粘度以量化无碰撞等离子体中的碰撞行为

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/ae08b4

Subash Adhikari, Carlos A. González, Yan Yang, 艳杨, Sean Oughton, Francesco Pecora, Riddhi Bandyopadhyay and William H. Matthaeus

{"title":"Estimation of Effective Viscosity to Quantify Collisional Behavior in Collisionless Plasma","authors":"Subash Adhikari, Carlos A. González, Yan Yang, 艳杨, Sean Oughton, Francesco Pecora, Riddhi Bandyopadhyay and William H. Matthaeus","doi":"10.3847/1538-4357/ae08b4","DOIUrl":"https://doi.org/10.3847/1538-4357/ae08b4","url":null,"abstract":"While dissipation in collisional plasma is defined in terms of viscosity and resistivity, the exact functional form of dissipation, i.e., the so-called dissipation function in nearly collisionless plasma, is unknown. Nevertheless, previous studies have suggested that there exists viscous-like energy conversion in collisionless plasma with scaling characteristics analogous to collisional plasma, and in particular that the average dissipation is proportional to the square of the rate of strain as in hydrodynamics. In this study, using 2.5D kinetic particle-in-cell (PIC) simulation of collisionless plasma turbulence, we provide an estimate of effective viscosity at each scale, obtained via a scale-filtering approach. We then compare the turbulent dynamics of the PIC simulation with that from MHD and two-fluid simulations in which the viscosity is equal to the effective viscosity estimate obtained from the PIC simulation. We find that the global behavior in these MHD and two-fluid simulations has a striking similarity to that in their kinetic/PIC counterpart. In addition, we explore the scale dependence of the effective viscosity and discuss implications of this approach for space plasmas.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282899","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}

引用次数: 0

Central Massive Black Holes Are Not Ubiquitous in Local Low-mass Galaxies 中心大质量黑洞在局部低质量星系中并不普遍

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/ae06a1

Fan Zou, Elena Gallo, Anil C. Seth, Edmund Hodges-Kluck, David Ohlson, Tommaso Treu, Vivienne F. Baldassare, W. N. Brandt, Jenny E. Greene, Piero Madau, Dieu D. Nguyen, Richard M. Plotkin, Amy E. Reines, Alberto Sesana, Jong-Hak Woo and Jianfeng Wu

{"title":"Central Massive Black Holes Are Not Ubiquitous in Local Low-mass Galaxies","authors":"Fan Zou, Elena Gallo, Anil C. Seth, Edmund Hodges-Kluck, David Ohlson, Tommaso Treu, Vivienne F. Baldassare, W. N. Brandt, Jenny E. Greene, Piero Madau, Dieu D. Nguyen, Richard M. Plotkin, Amy E. Reines, Alberto Sesana, Jong-Hak Woo and Jianfeng Wu","doi":"10.3847/1538-4357/ae06a1","DOIUrl":"https://doi.org/10.3847/1538-4357/ae06a1","url":null,"abstract":"The black hole occupation fraction (focc) defines the fraction of galaxies that harbor central massive black holes (MBHs), irrespective of their accretion activity level. While it is widely accepted that focc is nearly 100% in local massive galaxies with stellar masses M⋆ ≳ 1010M⊙, it is not yet clear whether MBHs are ubiquitous in less-massive galaxies. In this work, we present new constraints on focc based on over 20 yr of Chandra imaging data for 1606 galaxies within 50 Mpc. We employ a Bayesian model to simultaneously constrain focc and the specific accretion-rate distribution function, p(λ), where the specific accretion rate is defined as λ = LX/M⋆, where LX is the MBH accretion luminosity in the 2–10 keV range. Notably, we find that p(λ) peaks around ; above this value, p(λ) decreases with increasing λ, following a power law that smoothly connects with the probability distribution of bona fide active galactic nuclei. We also find that the occupation fraction decreases dramatically with decreasing M⋆: in high-mass galaxies (M⋆ ≈ 1011−12 M⊙), the occupation fraction is >93% (a 2σ lower limit), and then declines to (1σ errors) between M⋆ ≈ 109−10 M⊙, and to in the dwarf galaxy regime between M⋆ ≈ 108−9 M⊙. Our results have significant implications for the normalization of the MBH mass function over the mass range most relevant for tidal disruption events, extreme mass ratio inspirals, and MBH merger rates that upcoming facilities are poised to explore.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282896","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}

引用次数: 0

Searching for Continuous Gravitational Waves in the Parkes Pulsar Timing Array Data Release 3 在帕克斯脉冲星定时阵列中寻找连续引力波

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/ae0719

Shi-Yi Zhao, Zu-Cheng Chen, Jacob Cardinal Tremblay, Boris Goncharov, Xing-Jiang Zhu, N. D. Ramesh Bhat, Małgorzata Curyło, Shi Dai, Valentina Di Marco, Hao Ding, George Hobbs, Agastya Kapur, Wenhua Ling, Tao Liu, Rami Mandow, Saurav Mishra, Daniel J. Reardon, Christopher J Russell, Ryan M. Shannon, Shuangqiang Wang, Lei Zhang and Andrew Zic

{"title":"Searching for Continuous Gravitational Waves in the Parkes Pulsar Timing Array Data Release 3","authors":"Shi-Yi Zhao, Zu-Cheng Chen, Jacob Cardinal Tremblay, Boris Goncharov, Xing-Jiang Zhu, N. D. Ramesh Bhat, Małgorzata Curyło, Shi Dai, Valentina Di Marco, Hao Ding, George Hobbs, Agastya Kapur, Wenhua Ling, Tao Liu, Rami Mandow, Saurav Mishra, Daniel J. Reardon, Christopher J Russell, Ryan M. Shannon, Shuangqiang Wang, Lei Zhang and Andrew Zic","doi":"10.3847/1538-4357/ae0719","DOIUrl":"https://doi.org/10.3847/1538-4357/ae0719","url":null,"abstract":"We present results from an all-sky search for continuous gravitational waves from individual supermassive binary black holes using the third data release of the Parkes Pulsar Timing Array (PPTA). Even though we recover a common-spectrum stochastic process, potentially induced by a nanohertz gravitational-wave background, we find no evidence of continuous waves. Therefore, we place upper limits on the gravitational-wave strain amplitude: in the most sensitive frequency range around 10 nHz, we obtain a sky-averaged 95% credibility upper limit of ≈ 7 × 10−15. Our search is sensitive to supermassive binary black holes with a chirp mass of ≥109M⊙ up to a luminosity distance of 50 Mpc for our least sensitive sky direction and 200 Mpc for the most sensitive direction. This work provides at least 4 times better sensitivity in the 1–200 nHz frequency band than our last search based on the PPTA’s first data release. We expect that PPTA will continue to play a key role in detecting continuous gravitational waves in the exciting era of nanohertz gravitational-wave astronomy.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"80 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282897","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}

引用次数: 0

Long-term Simultaneous 2.25/8.60 GHz Monitoring of the Newly Discovered Repeating FRB 20240114A 新发现重复射电暴20240114A的2.25/8.60 GHz长期同步监测

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/adfece

Xiao-Wei Wang, 啸威王, Zhen Yan, 振闫, Zhi-Qiang Shen, 志强沈, Ke-Jia Lee, 柯伽李, Ya-Jun Wu, 亚军吴, Rong-Bing Zhao, 融冰赵, Jie Liu, 杰刘, Rui Wang, 睿王, Kuo Liu, 阔刘, Yuan-Chuan Zou, 远川邹, Zhi-Peng Huang, 志鹏黄, Chu-Yuan Zhang, 楚原张, Fan Yang, 帆杨, Zhen-Long Liao, 振龙廖, Yang-Yang Lin and 扬洋林

{"title":"Long-term Simultaneous 2.25/8.60 GHz Monitoring of the Newly Discovered Repeating FRB 20240114A","authors":"Xiao-Wei Wang, 啸威王, Zhen Yan, 振闫, Zhi-Qiang Shen, 志强沈, Ke-Jia Lee, 柯伽李, Ya-Jun Wu, 亚军吴, Rong-Bing Zhao, 融冰赵, Jie Liu, 杰刘, Rui Wang, 睿王, Kuo Liu, 阔刘, Yuan-Chuan Zou, 远川邹, Zhi-Peng Huang, 志鹏黄, Chu-Yuan Zhang, 楚原张, Fan Yang, 帆杨, Zhen-Long Liao, 振龙廖, Yang-Yang Lin and 扬洋林","doi":"10.3847/1538-4357/adfece","DOIUrl":"https://doi.org/10.3847/1538-4357/adfece","url":null,"abstract":"We report on the simultaneous monitoring of the repeating fast radio burst (FRB) 20240114A at 2.25 and 8.60 GHz, conducted 66 times between 2024 January 29 and 2025 February 15 with the Shanghai Tianma Radio Telescope. In about 180 hr of observation, we detected 155 bursts at 2.25 GHz above a fluence threshold of 0.72 Jy ms but none at 8.60 GHz above a fluence threshold of 0.27 Jy ms. FRB 20240114A exhibited frequency-dependent activity, as evidenced by the nondetections in 14.3 hr of observations at 2.25 GHz prior to 2024 February 24, despite its reported activity below 2 GHz. In contrast to its low-activity state reported below 1.4 GHz between 2024 June and December, FRB 20240114A exhibited high activity at 2.25 GHz in 2024 July with a mean burst rate of , followed by a low-activity state. We also detected a short-term reactivation at 2.25 GHz around 2025 January 20, about 2 weeks after renewed activity was reported below 1.4 GHz by other telescopes. The median burst width at 2.25 GHz is 3 ms, which is narrower than that at lower frequencies. The waiting time distribution peaks at 1019 s, and bursts arrive on hourly timescales consistent with a Poisson process. The isotropic-equivalent energy of the bursts spans 1037–1039 erg. The distribution of burst energy above the completeness threshold (7.5 × 1037 erg) follows a power-law relation with an index of γ = −1.20 ± 0.03 ± 0.02. Finally, we find that FRB 20240114A is at least 2 orders of magnitude less active at 8.60 GHz than at 2.25 GHz, and we constrain the broadband spectra of the detected bursts.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282892","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}

引用次数: 0

Electron Acceleration in Thinning Nonreconnecting Current Sheets in a Quasi-parallel Shock 准平行激波中非重新连接电流片变薄的电子加速

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/ae0327

N. Bessho, L.-J. Chen, M. Hesse, J. Ng, L. B. Wilson and J. E. Stawarz

{"title":"Electron Acceleration in Thinning Nonreconnecting Current Sheets in a Quasi-parallel Shock","authors":"N. Bessho, L.-J. Chen, M. Hesse, J. Ng, L. B. Wilson and J. E. Stawarz","doi":"10.3847/1538-4357/ae0327","DOIUrl":"https://doi.org/10.3847/1538-4357/ae0327","url":null,"abstract":"We study electron energization in turbulence-generated current sheets in the shock transition region by means of fully kinetic collisionless plasma simulations and theory. Using parameters in the Earth’s bow shock, we perform a two-dimensional particle-in-cell simulation of a quasi-parallel shock. In shock turbulence, many current sheets are produced, including those exhibiting magnetic reconnection and those that are not reconnecting. The electron temperature is enhanced in nonreconnecting current sheets as well as in reconnecting current sheets and magnetic islands. Performing electron trajectory tracing analysis, we find that energetic electrons are produced in nonreconnecting thinning current sheets. The motional electric field during the thinning process of a current sheet energizes both magnetized and unmagnetized electrons. We analytically show that the energization rate for unmagnetized electrons is slightly less than that of adiabatic energization for magnetized electrons, but unmagnetized electrons can be effectively trapped in magnetic field structures formed in thinning current sheets and continue to be energized. These nonreconnecting current sheets produce energetic electrons whose energies are comparable to the energetic electrons produced in magnetic islands, and they can reach the injection energy for diffusive shock acceleration, which is an acceleration mechanism for producing cosmic rays. The number of electrons that are energized in nonreconnecting current sheets is about a quarter of that in reconnection regions. The energization mechanism can be applicable to various space and astrophysical environments, including planetary bow shocks and supernova remnant shocks.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282894","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}

引用次数: 0

The Response of Warm Absorbers to the Variations in the Ionizing Continuum in the Active Galaxy NGC 4051 活动星系ngc4051中热吸收体对电离连续谱变化的响应

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/ae032f

Dev R. Sadaula, Timothy R. Kallman and Sibasish Laha

{"title":"The Response of Warm Absorbers to the Variations in the Ionizing Continuum in the Active Galaxy NGC 4051","authors":"Dev R. Sadaula, Timothy R. Kallman and Sibasish Laha","doi":"10.3847/1538-4357/ae032f","DOIUrl":"https://doi.org/10.3847/1538-4357/ae032f","url":null,"abstract":"We present a time-resolved X-ray spectral analysis of the warm absorbers in the Seyfert galaxy NGC 4051, which has an active galactic nucleus (AGN), using observations from the Neutron Star Interior Composition Explorer (NICER). Despite NICER’s moderate spectral resolution, its high-cadence monitoring allows us to probe the response of the ionized outflows, also known as warm absorbers, on timescales of ∼5500 s. We detect two distinct components of ionized absorbers in this source. The variability in the ionization parameter of the low-ionization warm absorber component, which tracks changes in the ionizing flux with no measurable time lag. This rapid response implies photoionization equilibrium and places a lower limit on the electron density of ≳9 × 106 cm−3 based on the most abundant ionic species, O VII. The absorber is located within ∼0.02 pc of the central source, consistent with an origin in the inner regions of the active nucleus. In contrast, the high-ionization absorber remains consistently under-ionized relative to equilibrium predictions. This suggests that it may be the collisional plasma, which was also detected in this source in the previous studies. These results demonstrate that time-resolved spectroscopy, even with moderate-resolution instruments, can provide valuable constraints on the density and location of warm absorbers in AGN. As a potential candidate source of AGN feedback, the study of these ionized outflows is crucial in understanding AGN–host galaxy interactions.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"124 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282895","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}

引用次数: 0

New TeV-emitting BL Lac Candidates from the eROSITA X-Ray Survey 来自eROSITA x射线调查的新tev发射BL Lac候选者

The Astrophysical Journal Pub Date : 2025-10-13 DOI: 10.3847/1538-4357/adff87

Cassidy Metzger, Andrea Gokus and Manel Errando

{"title":"New TeV-emitting BL Lac Candidates from the eROSITA X-Ray Survey","authors":"Cassidy Metzger, Andrea Gokus and Manel Errando","doi":"10.3847/1538-4357/adff87","DOIUrl":"https://doi.org/10.3847/1538-4357/adff87","url":null,"abstract":"TeV-emitting BL Lac–type blazars represent the extreme end of the blazar population. They are characterized by relatively weak jets and radiatively inefficient accretion disks. Particles accelerated in these jets experience fewer radiative losses, allowing them to reach energies beyond the TeV scale and produce TeV gamma-ray emission. The study of TeV blazars is constrained by the limited number of known sources in this category. Currently, only 56 high-synchrotron-peaked BL Lacs have been detected at energies above 0.1 TeV. Searches for TeV emission from BL Lacs typically target sources with bright X-ray emission and a synchrotron peak at or above 1 keV. The recently released eRASS1 catalog by the eROSITA collaboration, which covers half of the sky, represents the deepest X-ray survey in the soft X-ray band to date. Utilizing the eROSITA survey, combined with infrared data from the Wide-field Infrared Survey Explorer and archival radio observations, we have identified 121 TeV-emitting blazar candidates. Our search introduces selection criteria based on the radio to infrared that remove quasar-like objects that have similar infrared spectra and X-ray fluxes as TeV-emitting BL Lacs. In our search, we find 23 objects that had not been detected in the ROSAT X-ray survey and 11 that have not been previously associated with blazars. The candidates resulting from our search are suitable for follow-up observations with currently operating imaging atmospheric Cherenkov telescopes, as well as future facilities like the CTAO Observatory.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"94 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145282891","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}

引用次数: 0