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arXiv 2021年

作者： Chen, Hai-Liang Tauris, Thomas M. Han, Zhanwen Chen, Xuefei Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Department of Physics and Astronomy Aarhus University Ny Munkegade 120 Aarhus C8000 Denmark Aarhus University Høegh-Guldbergs Gade 6B Aarhus C8000 Denmark University of the Chinese Academy of Sciences Yuquan Road 19 Shijingshan Block Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Bejing100012 China

Close-orbit low-mass X-ray binaries (LMXBs), radio binary millisecond pulsars (BMSPs) with extremely low-mass helium WDs (ELM He WDs) and ultra-compact X-ray binaries (UCXBs) are all part of the same evolutionary sequence. It is therefore of uttermost importance to understand how these populations evolve from one specie to another. Moreover, UCXBs are important gravitational wave (GW) sources and can be detected by future space-borne GW observatories. However, the formation and evolutionary link between these three different populations of neutron star (NS) binaries are not fully understood. In particular, a peculiar fine-tuning problem has previously been demonstrated for the formation of these systems. In this investigation, we test a newly suggested magnetic braking prescription and model the formation and evolution of LMXBs. We compute a grid of binary evolution models and present the initial parameter space of the progenitor binaries which successfully evolve all the way to produce UCXBs. We find that the initial orbital period range of LMXBs, which evolve into detached NS+ELM He WD binaries and later UCXBs, becomes significantly wider compared to evolution with a standard magnetic braking prescription, and thus helps to relieve the fine-tuning problem. However, we also find that formation of wide-orbit BMSPs is prohibited for strong versions of this new magnetic braking prescription, which therefore calls for a revision of the prescription. Finally, we present examples of the properties of UCXBs as Galactic GW sources and discuss their detection by the LISA, TianQin and Taiji observatories. © 2021, CC BY-NC-SA.

关键词： Gravity waves

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Spectral diversities of gamma-ray bursts in high energy bands: Hints from turbulent cascade

arXiv

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arXiv 2020年

作者： Mao, Jirong Li, Liande Wang, Jiancheng Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan Province650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China University of Chinese Academy of Sciences Beijing100049 China

We statistically examine the gamma-ray burst (GRB) photon indices obtained by the Fermi-GBM and Fermi-LAT observations and compare the LAT GRB photon indices to the GBM GRB photon indices. We apply the jitter radiation to explain the GRB spectral diversities in the high-energy bands. In our model, the jitter radiative spectral index is determined by the spectral index of the turbulence. We classify GRBs into three classes depending on the shape of the GRB high-energy spectrum when we compare the GBM and LAT detections: the GRB spectrum is concave (GRBs turn out to be softer and are labeled as S-GRBs), the GRB spectrum is convex (GRBs turn out to be harder and are labeled as H-GRBs), and the GRBs have no strong spectral changes (labeled as N-GRBs). A universal Kolmogorov index 7/3 in the turbulent cascade is consistent with the photon index of the N-GRBs. The S-GRB spectra can be explained by the turbulent cascade due to the kinetic magnetic reconnection with the spectral index range of the turbulence from 8/3 to 3.0. The H-GRB spectra originate from the inverse turbulent cascade with the spectral index range of the turbulence from 2.0 to 3.5 that occurred during the large lengthscale magnetic reconnection. Thus, the GRB radiative spectra are diversified because the turbulent cascade modifies the turbulent energy spectrum. More observational samples are expected in the future to further identify our suggestions. Copyright © 2020, The Authors. All rights reserved.

关键词： Stars

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A potential mass-gap black hole in a wide binary with a circular orbit

arXiv

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arXiv 2024年

作者： Wang, Song Zhao, Xinlin Feng, Fabo Ge, Hongwei Shao, Yong Cui, Yingzhen Gao, Shijie Zhang, Lifu Wang, Pei Li, Xue Bai, Zhongrui Yuan, Hailong Huang, Yang Yuan, Haibo Zhang, Zhixiang Yi, Tuan Xiang, Maosheng Li, Zhenwei Li, Tanda Zhang, Junbo Zhang, Meng Han, Henggeng Fan, Dongwei Li, Xiangdong Chen, Xuefei Liu, Zhengwei Meng, Xiangcun Liu, Qingzhong Zhang, Haotong Gu, Wei-Min Liu, Jifeng Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China School of Astronomy and Space Sciences University of Chinese Academy of Sciences Beijing100049 China Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai201210 China School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China School of Astronomy and Space Science Nanjing University Nanjing210023 China Ministry of Education Nanjing210023 China CAS Key Laboratory of FAST NAOC Chinese Academy of Sciences Beijing100101 China Department of Astronomy Beijing Normal University Beijing100875 China Department of Astronomy Xiamen University Fujian Xiamen361005 China Department of Astronomy School of Physics Peking University Beijing100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 China College of Physics and Electronic Engineering Qilu Normal University Jinan China New Cornerstone Science Laboratory National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China

Mass distribution of black holes identified through X-ray emission suggests a paucity of black holes in the mass range of 3 to 5 solar masses. Modified theories have been devised to explain this mass gap, and it is suggested that natal kicks during supernova explosion can more easily disrupt binaries with lower mass black holes. Although recent LIGO observations reveal the existence of compact remnants within this mass gap, the question of whether low-mass black holes can exist in binaries remains a matter of debate. Such a system is expected to be noninteracting without X-ray emission, and can be searched for using radial velocity and astrometric methods. Here we report Gaia DR3 3425577610762832384, a wide binary system including a red giant star and an unseen object, exhibiting an orbital period of approximately 880 days and near-zero eccentricity. Through the combination of radial velocity measurements from LAMOST and astrometric data from Gaia DR2 and DR3 catalogs, we determine a mass of (Equation presented) M☉ of the unseen component. This places the unseen companion within the mass gap, strongly suggesting the existence of binary systems containing low-mass black holes. More notably, the formation of its surprisingly wide circular orbit challenges current binary evolution and supernova explosion theories. Copyright © 2024, The Authors. All rights reserved.

关键词： Supernovae

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An explanation for 13 consecutive days activities of Mrk 421

arXiv

引用

arXiv 2020年

作者： Zheng, Y.G. Yang, C.Y. Kang, Shi-Ju Bai, J.M. Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Department of Physics Yunnan Normal University Kunming650092 China Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment-Shandong University Weihai264209 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences China Department of Physics and Electronics Science Liupanshui Normal University LiupanshuiGuizhou553004 China

It is surprising to find a fact for migration in the peak positions of synchrotron spectra energy distribution component during in the activity epochs of Mrk 421, accompanying with an orphan flaring at the X-ray and GeV-TeV γ-ray bands. A geometric interpretation and standard shock or stochastic acceleration models of blazar emission have difficulty reproducing these observed behaviours. The present paper introduces a linear acceleration by integrating the reconnection electric field into the particle transport model for the observed behaviours of Mrk 421. We note that the strong evidence for evolution of multi-wavelength spectral energy distribution characteristic by shifting the peak frequency, accompanying with an orphan flaring at the X-ray and GeV-TeV γ-ray bands provides an important electrostatic acceleration diagnostic in blazar jet. Assuming suitable model parameters, we apply the results of the simulation to the 13-day flaring event in 2010 March of Mrk 421, concentrating on the evolution of multi-wavelength spectral energy distribution characteristic by shifting the peak frequency. It is clear that the ratio of the electric field and magnetic field strength plays an important role in temporal evolution of the peak frequency of synchrotron spectral energy distribution component. We suggest the electrostatic acceleration responsible for the evolution of multi-wavelength spectral energy distribution characteristic by shifting the peak frequency is reasonable. Based on the model results, we issue that the peak frequency of the synchrotron spectral energy distribution component may denote a temporary characteristic of blazars, rather than a permanent one. Copyright © 2020, The Authors. All rights reserved.

关键词： Spectroscopy

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The evolution of the Supersoft X-Ray Source WX Cen Dominated by Magnetic Wind

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Astrophysical Journal 2023年第1期944卷 97-97页

作者： Zang, Lei Qian, Shengbang Fernández-Lajús, Eduardo Yunnan Observatories Chinese Academy of Sciences (CAS) P.O. Box 110 Yunnan Kunming 650011 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Yunnan Kunming 650011 China University of Chinese Academy of Sciences Yuquan Road 19# Shijingshan District Beijing 100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District 100012 Beijing China Facultad de Ciencias Astronómicas y Geofísicas Universidad Nacional de La Plata Paseo del Bosque S/N— La Plata B1900FWA Argentina Instituto de Astrofísica de La Plata (CCT La Plata—CONICET/UNLP) La Plata B1900FWA Argentina

WX Cen is most likely one of the Galactic counterparts of compact binary supersoft X-ray sources as a member of the V Sagittae class, in which mass is transferred from a donor secondary to a massive white dwarf primary via an accretion disk. Based on the photometric observations from the TESS space telescope and AAVSO database, 218 times of light minimum were determined. By collecting all available eclipse timings of WX Cen from the literature together with those newly determined, we constructed an O−C diagram and analyzed the variations in the orbital period of the eclipsing binary. It is confirmed that the orbital period is continuously decreasing and the rate of the change in the orbital period is revised to P ̇ = − 4.4 ( 4 ) × 10 − 7 day yr − 1 = − 0.038 ( 3 ) s yr − 1 . The mass of the donor secondary is estimated as M _s ∼ 0.6 M _⊙, when the white dwarf mass is M _WD ∼ 0.9 M _⊙. By considering a conservative mass transfer from the secondary to the primary, the orbital period of WX Cen should be increasing, which is opposite to the observed continuous decrease. Therefore, the decrease in the period can be plausibly explained as the result of angular momentum loss (AML) via magnetic wind from the secondary and/or from the accretion disk. The AML causes the donor secondary with a low mass to continually be filling its critical Roche lobe and transferring material to the white dwarf. In this way, the evolution of WX Cen is dominated by the magnetic wind and continuously radiating supersoft X-rays. © 2023. The Author(s). Published by the American Astronomical Society.

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Black hole immersed dark matter halo

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Physical Review D 2020年第2期101卷 024029-024029页

作者： Zhaoyi Xu Xiaobo Gong Shuang-Nan Zhang Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming 650216 China University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming 650216 China National Astronomical Observatories of China Chinese Academy of Sciences Beijing 100012 China

In this work, based on the constant for the equation of state ω, we obtain the Schwarzschild-like black hole solutions in some dark matter halos. We also generalize these black hole metrics to Kerr-like black hole solutions with Newman-Janis algorithm. For an example, we derive the specific black hole space-time metrics in the case of the cold dark matter halo and Bose-Einstein condensation dark matter halo. Following the above two black hole metrics, we discuss how a dark matter halo changes the properties of black holes, including the event horizon structure (these results agree with that obtained by Liu and Zhang [Phys. Lett. B 679, 88 (2009).] in the case of gravitational collapse), stationary limit surfaces, ergosphere, and singularity structure. Our results may help us understand the interaction between the dark matter halo and supermassive black holes at the centers of galaxies.

关键词： Alternative gravity theories Astrophysical studies of gravity

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Bvri Light Curves, Period and Spectroscopic Study of a Low Mass-Ratio Contact Binary Hv Aqr

SSRN

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SSRN 2022年

作者： Zubairi, Ahmed Waqas Zhou, Xiao Lajs, Eduardo Ferncndez Zhu, Liying Liao, Wenping Soonthornthum, Boonrucksar Zhang, Bin Sarotsakulchai, Nopphadon Yunnan Observatories Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Yuquan Road 19 Sijingshang Block Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100101 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Facultad de Ciencias Astronmicas y Geofisicas Universidad Nacional de La Plata Buenos Aires La Plata1900 Argentina Instituto de Astroflsica de La Plata CCT La plata - CONICET UNLP Argentina National Astronomical Research Institute of Thailand 260 Moo 4 T. Donkaew A. Maerim Chiangmai50180 Thailand School of Physics and Electronic Science Guizhou Normal University Guiyang550001 China

New BVRI light curves of the short period binary system, {\astrobj}, are presented. Photometric solutions were derived using the 2015 version of Wilson–Devinney code. The complete eclipses of the light curves of {\astrobj}\, enable us to determine high-precision photometric parameters of the binary system. The new solution suggest that {\astrobj}\, is a low mass ratio ($q=0.145$) deep contact binary with a contact degree of $f =74.19\%$. Based on all available times of light minimum, we analyzed the long-term period changes of {\astrobj}. A decrease rate of $dP/dt=-9.01\times 10^{-8} days/yr$ was determined. The continuous period decrease can be explained by the mass transfer from the primary component to the secondary and angular momentum loss via magnetic stellar wind. A conservative mass transfer rate of $1.876 \times 10^{-8} M_{\odot} yr^{-1}$ and angular momentum loss rate at $6.25 \times 10^{39} Kg\,m^2\,s^{-1} \, yr^{-1}$ were derived. As the orbital period decreases, the contact degree of {\astrobj}\, will become deeper and finally it will evolve into a single rapid-rotating star. © 2022, The Authors. All rights reserved.

关键词： Mass transfer

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SN 2019ein: A Type Ia Supernova Likely Originated from a Sub-Chandrasekhar-Mass Explosion

arXiv

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arXiv 2022年

作者： Xi, Gaobo Wang, Xiaofeng Li, Wenxiong Mo, Jun Zhang, Jujia Liu, Jialian Chen, Zhihao Filippenko, Alexei V. Zheng, Weikang Brink, Thomas G. Zhang, Xinghan Sai, Hanna Ehgamberdiev, Shuhrat A. Mirzaqulov, Davron Zhang, Jicheng Physics Department Tsinghua Center for Astrophysics Tsinghua University Beijing100084 China Beijing Planetarium Beijing Academy of Science and Technology Beijing100044 China The School of Physics and Astronomy Tel Aviv University Tel Aviv69978 Israel Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy University of California BerkeleyCA94720-3411 United States Ulugh Beg Astronomical Institute Uzbekistan Academy of Sciences Tashkent100052 Uzbekistan National University of Uzbekistan Tashkent100174 Uzbekistan Department of Astronomy Beijing Normal University Beijing100875 China

We present extensive optical photometric and spectroscopic observations for the nearby Type Ia supernova (SN Ia) 2019ein, spanning the phases from ∼ 3 days to ∼ 330 days after the explosion. This SN Ia is characterized by extremely fast expansion at early times, with initial velocities of Si II and Ca II being above ∼ 25, 000–30,000 km s−1. After experiencing an unusually rapid velocity decay, the ejecta velocity dropped to ∼ 13, 000 km s−1 around maximum light. Photometrically, SN 2019ein has a moderate post-peak decline rate (Δm15(B) = 1.35 ± 0.01 mag), while being fainter than normal SNe Ia by about 40% (with MBmax ≈ −18.71 ± 0.15 mag). The nickel mass synthesized in the explosion is estimated to be 0.27–0.31 M from the bolometric light curve. Given such a low nickel mass and a relatively high photospheric velocity, we propose that SN 2019ein likely had a sub-Chandrasekhar-mass white dwarf (WD) progenitor, MWD . 1.22 M . In this case, the explosion could have been triggered by a double-detonation mechanism, for which 1- and 2-dimensional models with WD mass MWD ≈ 1 M and a helium shell of 0.01 M can reasonably produce the observed bolometric light curve and spectra. The predicted asymmetry as a result of double detonation is also favored by the redshifted Fe II and Ni II lines observed in the nebular-phase spectrum. Possible diversity in origin of high velocity SNe Ia is also discussed. Copyright © 2022, The Authors. All rights reserved.

关键词： Supernovae

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ONe WD+He star systems as the progenitors of IMBPs

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Proceedings of the International Astronomical Union 2019年第S346期14卷 478-479页

作者： Wang, Bo Liu, Dongdong Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China

Previous theoretical studies can only explain part of the observed intermediate-mass binary pulsars (IMBPs) with short orbital periods. Note that an ONe white dwarf (WD) accreting mass from a He star may experience the accretion-induced collapse process and eventually form IMBPs, known as the ONe WD+He star scenario. By investigating the evolution of a large number of ONe WD+He star binaries, we found that the ONe WD+He star scenario can form IMBPs including pulsars with 5 - 340 ms spin periods, and the orbital periods range from 0.04 to 900 d. Compared with the observed IMBPs, this scenario can cover almost all of the IMBPs with short orbital periods. Thus, we suggest that the ONe WD+He star channel is responsible for the formation of IMBPs with short orbital periods. © International Astronomical Union 2019.

关键词： binaries: close stars: evolution stars: neutron white dwarfs

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A spectral data release for 104 Type II Supernovae from the Tsinghua Supernova Group

arXiv

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arXiv 2024年

作者： Lin, Han Wang, Xiaofeng Zhang, Jujia Xiang, Danfeng Zhang, Tianmeng Zhao, Xulin Zhang, Xinghan Sai, Hanna Rui, Liming Mo, Jun Xi, Gaobo Huang, Fang Li, Xue Cai, Yongzhi Lin, Weili Lin, Jie Wu, Chengyuan Zhang, Jicheng Chen, Zhihao Li, Zhitong Li, Wenxiong Li, Linyi Zhang, Kaicheng Miao, Cheng Chen, Juncheng Fan, Zhou Fu, Jianning Qian, Shengbang Wu, Hong Wu, Xue-Bing Yan, Jingzhi Zhang, Huawei Zhang, Junbo Zhang, Liyun Zheng, Jie Zhai, Qian Yan, Shengyu Physics Department Tsinghua University Beijing100084 China Key Laboratory of Radio Astronomy and Technology Chinese Academy of Sciences A20 Datun Road Chaoyang District Beijing100101 China Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China Key Laboratory of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Beijin China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China School of Science Tianjin University of Technology Tianjin300384 China School of Physics and Information Engineering Jiangsu Second Normal University Jiangsu Nanjing211200 China Department of Astronomy Shanghai Jiao Tong University Shanghai200240 China Department of Astronomy University of Science and Technology Hefei China Department of Astronomy Beijing Normal University Beijing1000875 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Wuzhou University China Department of Astronomy School of Physics and Astronomy Yunnan University Kunming650091 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Department of Astronomy School of Physics Peking University Beijing100871 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing China College of Physics Guizhou University Guiyang China

We present 206 unpublished optical spectra of 104 type II supernovae obtained by the Xinglong 2.16m telescope and Lijiang 2.4m telescope during the period from 2011 to 2018, spanning the phases from about 1 to 200 days after the SN explosion. The spectral line identifications, evolution of line velocities and pseudo equivalent widths, as well as correlations between some important spectral parameters are presented. Our sample displays a large range in expansion velocities. For instance, the Fe ii 5169 velocities measured from spectra at t ∼ 50 days after the explosion vary from 2000 km s−1 to 5500 km s−1, with an average value of 3872 ± 949 km s−1. Power-law functions can be used to fit the velocity evolution, with the power-law exponent quantifying the velocity decline rate. We found an anticorrelation existing between Hβ velocity at mid-plateau phase and its velocity decay exponent, SNe II with higher velocities tending to have smaller velocity decay rate. Moreover, we noticed that the velocity decay rate inferred from the Balmer lines (i.e., Hα and Hβ) have moderate correlations with the ratio of absorption to emission for Hα (a/e). In our sample, two objects show possibly flash-ionized features at early phases. Besides, we noticed that multiple high-velocity components may exist on the blue side of hydrogen lines of SN 2013ab, possibly suggesting that these features arise from complex line forming region. All our spectra can be found in WISeREP and Zenodo. Copyright © 2024, The Authors. All rights reserved.

关键词： Supernovae

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