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arXiv 2023年

作者： Zhang, Yuexin Méndez, Mariano Motta, Sara E. Zdziarski, Andrzej A. Marcel, Grégoire García, Federico Altamirano, Diego Belloni, Tomaso M. Zhang, Liang Timmermans, Thimo Zhang, Guobao Kapteyn Astronomical Institute University of Groningen P.O. BOX 800 Groningen9700 AV Netherlands Center for Astrophysics Harvard & Smithsonian 60 Garden St CambridgeMA02138 United States MerateI-23807 Italy Nicolaus Copernicus Astronomical Center Polish Academy of Sciences Bartycka 18 WarszawaPL-00-716 Poland Institute of Astronomy University of Cambridge Madingley Road CambridgeCB3 0HA United Kingdom Villa Elisa Buenos Aires1894 Argentina School of Physics and Astronomy University of Southampton SouthamptonSO17 1BJ United Kingdom Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China

The high-frequency bump, characterized by a frequency exceeding ∼30 Hz, represents a seldom-explored time-variability feature in the power density spectrum (PDS) of black-hole X-ray binaries. In the 2002, 2004, 2007 and 2010 outbursts of GX 339−4, the bump has been occasionally observed in conjunction with type-C quasi-periodic oscillations (QPOs). We systematically study the properties of the bump during these four outbursts observed by Rossi X-ray Timing Explorer (RXTE) in the 2-60 keV bands and detect the bump in 39 observations. While the frequencies of the type-C QPOs are in the range of ∼0.1-9 Hz, the root-mean-square (rms) amplitude of the bump shows an evolution in the hardness ratio versus the type-C QPO frequency plot. By comparing the rms amplitude of the bump with the corona temperature and simultaneous radio jet flux of the source, as previously studied in GRS 1915+105, we establish that in the hard state of GX 339−4, the bump is always strong, with the measurements of the rms amplitude in the range of 4-10%. At the same time, the corona temperature is high and the radio flux is low. These findings indicate that, using the bump as a proxy, the majority of the accretion energy is directed towards the hot corona rather than being channeled into the radio jet. We discuss this phenomenon in terms of an inefficient energy transfer mechanism between the corona and jet in GX 339−4. © 2023, CC BY.

关键词： Black holes

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Minute-Cadence Observations of the LAMOST Fields with the TMTS: IV— Catalog of Cataclysmic Variables from the First 3-yr Survey

arXiv

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arXiv 2024年

作者： Liu, Qichun Lin, Jie Wang, Xiaofeng Dai, Zhibin Sun, Yongkang Xi, Gaobo Mo, Jun Liu, Jialian Yan, Shengyu Filippenko, Alexei V. Brink, Thomas G. Yang, Yi Patra, Kishore C. Cai, Yongzhi Chen, Zhihao Chen, Liyang Guo, Fangzhou Jiang, Xiaojun Li, Gaici Li, Wenxiong Lin, Weili Miao, Cheng Ma, Xiaoran Peng, Haowei Xia, Qiqi Xiang, Danfeng Zhang, Jicheng Physics Department Tsinghua Center for Astrophysics Tsinghua University Beijing100084 China CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei230026 China School of Astronomy and Space Sciences University of Science and Technology of China Hefei230026 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100049 China Department of Astronomy University of California BerkeleyCA94720-3411 United States International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100101 China Department of Astronomy Xiamen University Xiamen361005 China Department of Astronomy Beijing Normal University Beijing100875 China

The Tsinghua University–Ma Huateng Telescopes for Survey (TMTS) started to monitor the LAMOST plates in 2020, leading to the discovery of numerous short-period eclipsing binaries, peculiar pulsators, flare stars, and other variable objects. Here, we present the uninterrupted light curves for a sample of 64 cataclysmic variables (CVs) observed/discovered using the TMTS during its first three-year observations, and we introduce new CVs and new light-variation periods (from known CVs) revealed through the TMTS observations. Thanks to the high-cadence observations of TMTS, diverse light variations, including superhumps, quasi-periodic oscillations, large-amplitude orbital modulations, and rotational modulations, are able to be detected in our CV samples, providing key observational clues for understanding the fast-developing physical processes in various CVs. All of these short-timescale light-curve features help further classify the subtypes of CV systems. We highlight the light-curve features observed in our CV sample and discuss further implications of minute-cadence light curves for CV identifications and classifications. Moreover, we examine the Hα emission lines in the spectra from our nonmagnetic CV samples (i.e., dwarf novae and nova-like subclasses) and find that the distribution of Hα emission strength shows significant differences between the sources with orbital periods above and below the period gap, which agrees with the trend seen from the SDSS nonmagnetic CV sample. Copyright © 2024, The Authors. All rights reserved.

关键词： Seismology

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On the injection of relativistic electrons in the jet of 3C 279

arXiv

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arXiv 2020年

作者： Hu, Wen Yan, Dahai Dai, Benzhong Zeng, Wei Hu, Qianglin College of Mathematics and Physics Jinggangshan University Jiangxi Province Jian343009 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatory Chinese Academy of Sciences Kunming650011 China Department of Astronomy Key Laboratory of Astroparticle Physics Yunnan Province Yunnan University Kunming650091 China

The acceleration of electrons in 3C 279 is investigated through analyzing the injected electron energy distribution (EED) in a time-dependent synchrotron self-Compton + external Compton emission model. In this model, it is assumed that relativistic electrons are continuously injected into the emission region, and the injected EED [Q′e(γ′)] follows a single power-law form with low- and high-energy cutoffs γmin′ and γmax′, respectively, and the spectral index n, i.e, Q′e(γ′) ∝ γ′−n. This model is applied to 14 quasi-simultaneous spectral energy distributions (SEDs) of 3C 279. The Markov Chain Monte Carlo fitting technique is performed to obtain the best-fitting parameters and the uncertainties on the parameters. The results show that the injected EED is well constrained in each state. The value of n is in the range of 2.5 to 3.8, which is larger than that expected by the classic non-relativistic shock acceleration. However, the large value of n can be explained by the relativistic oblique shock acceleration. The flaring activity seems to be related to an increased acceleration efficiency, reflected in an increased γmin′ and electron injection power. Copyright © 2020, The Authors. All rights reserved.

关键词： Gamma rays

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Reverberation Mapping of Two Variable Active Galactic Nuclei: Probing the Distinct Characteristics of the Inner and Outer Broad-line Regions

arXiv

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arXiv 2024年

作者： Feng, Hai-Cheng Li, Sha-Sha Bai, J.M. Liu, H.T. Lu, Kai-Xing Pang, Yu-Xuan Sun, Mouyuan Wang, Jian-Guo Xu, Yerong Zhang, Yang-Wei Zhou, Shuying Yunnan Observatories Chinese Academy of Sciences Yunnan Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Yunnan Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory of Radio Astronomy and Technology Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100101 China Department of Astronomy School of Physic Peking University Beijing100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Department of Astronomy Xiamen University Fujian Xiamen361005 China INAF - IASF Palermo Via U. La Malfa 153 PalermoI-90146 Italy Department of Astronomy & Physics Saint Mary's University 923 Robie Street HalifaxNSB3H 3C3 Canada South-Western Institute for Astronomy Research Yunnan University Kunming650500 China

Current reverberation mapping (RM) studies primarily focus on single emission lines, particularly the Hβ line, which may not fully reveal the geometry and kinematic properties of the broad-line region (BLR). To overcome this limitation, we conducted multiline RM observations on two highly variable active galactic nuclei (AGNs), KUG 1141+371 and UGC 3374, using the Lijiang 2.4 m telescope. Our goal was to investigate the detailed structure of different regions within the BLR. We measured the time lags of multiple broad emission lines (Hα, Hβ, Hγ, He I, and He II) and found clear evidence of radial ionization stratification in the BLRs of both AGNs. Velocity-resolved RM analysis revealed distinct geometry and kinematics between the inner and outer regions of the BLRs. Assuming that velocity-resolved lags reflect the kinematics of BLR, our observations indicate that: (1) in KUG 1141+371, the inner BLR exhibits outflow signatures, while the outer region is consistent with virialized motion;(2) in UGC 3374, the inner region displays virial motion, while the outer region shows inflow. Furthermore, we detected "breathing" behavior in the outer BLR regions of both AGN, while the inner BLR regions show "anti-breathing", which may be linked to intrinsic BLR properties. We discuss these findings in the context of various BLR formation models, highlighting importance of long-term, multiline RM campaigns in understanding of BLR structure and evolution. Additionally, our results suggest that the observed stratification in BLR geometry and kinematics may contribute to the scatter in black hole mass estimates and the rapid changes in velocity-resolved RM signatures reported in recent studies. © 2024, CC BY.

关键词： Active Galactic Nuclei

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Evidence of Stellar Oscillations in the Post-common-envelope Binary Candidate ASASSN-V J205543.90+240033.5

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Astrophysical Journal Letters 2023年第2期953卷 L17-L17页

作者： Takata, J. Kong, A.K.H. Wang, X.F. Song, F.F. Mao, J. Hou, X. Hu, C.-P. Lin, L.C.-C. Li, K.L. Hui, C.Y. Department of Astronomy School of Physics Huazhong University of Science and Technology Wuhan 430074 China Institute of Astronomy National Tsing Hua University Hsinchu 30013 Taiwan Yunnan Observatories Chinese Academy of Sciences Yunnan Province Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China University of Chinese Academy of Sciences Beijing 100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing 100012 China Department of Physics National Changhua University of Education Changhua 50007 Taiwan Department of Physics National Cheng Kung University Tainan 701401 Taiwan Department of Astronomy and Space Science Chungnam National University Daejeon 305-764 South Korea

ASASSN-V J205543.90+240033.5 (ASJ2055) is a possible post-common-envelope binary system. Its optical photometric data show an orbital variation of about 0.52 days and a fast period modulation of P ₀ ∼ 9.77 minutes, whose origin is unknown. In this Letter, we report evidence of the stellar oscillation of the companion star as the origin of the fast period modulation. We analyze the photometric data taken by the Transiting Exoplanet Survey Satellite, the Liverpool Telescope, and the Lulin One-meter Telescope. It is found that the period of the 9.77 minutes signal measured in 2022 August is significantly shorter than that in 2021 July/August, and the magnitude of the change is of the order of ∣△P ₀∣/P ₀ ∼ 0.0008(4). Such a large variation will be incompatible with the scenario of the white dwarf (WD) spin as the origin of the 9.77 minutes periodic modulation. We suggest that the fast periodic signal is related to the emission from the irradiated companion star rather than that of the WD. Using existing photometric data covering a wide wavelength range, we estimate that the hot WD in ASJ2055 has a temperature of T _eff ∼ 80,000 K and is heating the oscillating M-type main-sequence star with T _eff ∼ 3500 K on its unirradiated surface. The stellar oscillation of the M-type main-sequence star has been predicted in theoretical studies, but no observational confirmation has been done. ASJ2055, therefore, has the potential to be a unique laboratory for investigating the stellar oscillation of an M-type main-sequence star and the heating effect on stellar oscillation. © 2023. The Author(s). Published by the American Astronomical Society.

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Error analysis of the light curve solution of contact binaries based on the W-D code

arXiv

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arXiv 2021年

作者： Liu, Liang Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 China

We use the idea of repeat measurement to determine the mean value and error of light curve solution parameters of contact binaries. Our simulation is realized by the Monte Carlo algorithm and Wilson-Devinney code. This method can obtain the systematic and random error simultaneously. Within our 48 models, the systematic errors are smaller than the random errors in most case. According to the numerical calculations, it is found that the relative errors of photometric mass ratios are less than 1% for totally eclipsing contact binaries, while they are generally between 10% and 20% for partly eclipsing ones. The effect of third light on the errors of photometric solution is also investigated. With a third light, these errors are close to 10% for totally eclipsing contact binaries. Specially, it is better to set the third light to zero in flux if that light is very faint (e.g., less than 1% contribution in luminosity), because such faint third light will bring big errors to the light curve solutions. © 2021, CC BY.

关键词： Stars

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WD mass and orbital period relation of sdB + He WD binaries

arXiv

引用

arXiv 2021年

作者： Zhang, Yangyang Chen, Hai-Liang Xiong, Heran Chen, Xuefei Han, Zhanwen Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of the Chinese Academy of Science Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Research School of Astronomy and Astrophysics Mount Stromlo Observatory Australian National University ACT2611 Australia

Most subdwarf B (sdB) + Helium white dwarf (He WD) binaries are believed to be formed from a particular channel. In this channel, the He WDs are produced first from red giants (RGs) with degenerate cores via stable mass transfer and sdB stars are produced from RGs with degenerate cores via common envelope (CE) ejection. They are important for the studies of CE evolution, binary evolution, and binary population synthesis. However, the relation between WD mass and orbital period of sdB + He WD binaries has not been specifically studied. In this paper, we first use a semi-analytic method to follow their formation and find a WD mass and orbital period relation. Then we use a detailed stellar evolution code to model their formation from main-sequence binaries. We find a similar relation between the WD mass and orbital period, which is in broad agreement with observations. For most sdB + He WD systems, if the WD mass (orbital period) can be determined, the orbital period (WD mass) can be inferred with this relation and then the inclination angle can be constrained with the binary mass function. In addition, we can also use this relation to constrain the CE ejection efficiency and find that a relative large CE ejection efficiency is favoured. If both the WD and sdB star masses can be determined, the critical mass ratios of dynamically unstable mass transfer for RG binaries can also be constrained. © 2021, CC BY.

关键词： White dwarfs

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The deep and low-mass-ratio contact binary CSS J022914.4+044340 with a luminous additional companion

arXiv

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arXiv 2021年

作者： Liu, Liang Li, Xu-Zhi Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 China

The first B-, V -, Rc-, and Ic-band light curves of CSS J022914.4+044340 are presented and analyzed. It is found that CSS J022914.4+044340 is a low mass ratio (0.198 ± 0.005) deep (63.7 ± 7.9 %) contact binary, indicating that it has been already at the end evolutionary stage of tidally-locked evolution via magnetized wind. Because of the totally eclipsing character, the photometric solutions are reliable. The temperature and the metallicity are determined from the spectroscopic data as T = 5855 ± 15 K, and [Fe/H] = −0.842 ± 0.031, respectively. Based on the parallax of Gaia EDR3, the physical parameters of CSS J022914.4+044340 are estimated as M1 = 1.44+0.25−0.22 M☉, M2 = 0.29+0.05−0.05 M☉, R1 = 1.26+0.08−0.06 R☉, R2 = 0.65+0.03−0.04 R☉, L1 = 1.718+0.186−0.191 L☉, L2 = 0.416+0.039−0.050 L☉. Combined the fraction in light of the third body via the photometric solution (54%), the luminosity of the third body is estimated as 2.705 L☉. The third body may be inferred as a subgiant. Thus, it is explained that why the primary component of CSS J022914.4+044340 has higher mass among the similar systems, and why its metallicity is so poor. © 2021, CC BY.

关键词： Photometry

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Revisiting the x-ray emission of the asynchronous polar V1432 aql

arXiv

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arXiv 2021年

作者： Qishan, Wang Shengbang, Qian Liying, Zhu P. O. Box 110 Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P. O. Box 110 Kunming650216 China University of Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Science 20A Datun Road Chaoyang Distric Beijing100012 China

As the only eclipsing asynchronous polar, V1432 Aql provides an excellent laboratory to study the interaction between the accreted matter and the magnetic field. Here, we report an analysis of the X-ray data from the contemporaneous NuSTAR and Swift-XRT observations. The X-ray data present a profile with a low-intensity state for almost half an orbital period, a dip at 0.6 phase, and a peak at 0.75 phase, which suggests that there was only one accretion region during the observation and the claim is supported by the spectral analysis. The comparison with the previous data indicates that the X-ray data have an orbital modulation, as the case in BeppoSAX, rather than a spin one observed in ROSAT. We attribute the orbit and spin modulations to the different accretion geometries at work. The spectral analysis of the wide-band data presents a significant reflection effect, a commonly observed soft X-ray temperature, and the energy balance in V1432 Aql . Additionally, we obtained a low total accretion rate of 1.3 × 10−10 M yr−1 and a high specific accretion rate of 3.8 g cm−2 s−1 which explains the strong reflection from the surface of the white dwarf. However, due to its complex emission, a more physical understanding of its accretion geometry is still outstanding. Copyright © 2021, The Authors. All rights reserved.

关键词： Spectrum analysis

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Asteroseismology of the DAV star R808

arXiv

引用

arXiv 2020年

作者： Chen, Yanhui H. Shu, Hong Institute of Astrophysics Chuxiong Normal University Chuxiong675000 China School of Physics and Electronical Science Chuxiong Normal University Chuxiong675000 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650011 China

The DAV star R808 was observed by 13 different telescopes for more than 170 hours in April 2008 on the WET run XCOV26. 25 independent pulsation frequencies were identified by this data set. We assumed 19 m = 0 modes and performed an asteroseismological study on those 19 modes. We evolve grids of DAV star models by WDEC adopting the element diffusion scheme with pure and screened Coulomb potential effect. The core compositions are from white dwarf models evolved by MESA, which are thermal nuclear burning results. Our best fitting model is from the screened Coulomb potential scenario, which has parameters of log(MHe/M∗) = -2.4, log(MH/M∗) = -5.2, Teff = 11100K, M∗ = 0.710M, logg = 8.194, and σRMS = 2.86s. The value of σRMS is the smallest among the four existing asteroseismological work. The average period spacing is 46.299s for l = 1 modes and 25.647s for l = 2 modes. The other 6 observed modes can be fitted by m 6= 0 components of some modes for our best fitting model. Fitting the 25 observed modes, we obtain a σRMS value of 2.59s. Considering the period spacings, we also assume, that at least in one case, we detect an l = 2 trapped mode. © 2020, CC-BY-SA.

关键词： White dwarfs

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