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AT2023lli: A Tidal Disruption Event with Prominent Optical Early Bump and Delayed Episodic X-ray Emission

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arXiv 2024年

作者： Huang, Shifeng Jiang, Ning Zhu, Jiazheng Wang, Yibo Wang, Tinggui Wang, Shan-Qin Gan, Wen-Pei Liang, En-Wei Qin, Yu-Jing Lin, Zheyu Xu, Lin-Na Cai, Min-Xuan Jiang, Ji-An Kong, Xu Li, Jiaxun Li, Long Wang, Jian-Guo Xu, Ze-Lin Xue, Yongquan Yuan, Ye-Fei Cheng, Jingquan Fan, Lulu Gao, Jie Hu, Lei Hu, Weida Li, Bin Li, Feng Liang, Ming Liu, Hao Liu, Wei Lou, Zheng Luo, Wentao Qian, Yuan Tang, Jinlong Wan, Zhen Wang, Hairen Wang, Jian Yang, Ji Yao, Dazhi Zhang, Hongfei Zhang, Xiaoling Zhao, Wen Zheng, Xianzhong Zhu, Qingfeng Zuo, Yingxi 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 Institute of Deep Space Sciences Deep Space Exploration Laboratory Hefei230026 China Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and Technology Guangxi University Nanning530004 China Nanjing Hopes Technology Co. Ltd. Pukou District Nanjing210000 China Division of Physics Mathematics and Astronomy California Institute of Technology 1200 E California Blvd. PasadenaCA91125 United States National Astronomical Observatory of Japan National Institutes of Natural Sciences Tokyo181-8588 Japan Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Kunming650011 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of China Hefei230026 China McWilliams Center for Cosmology Department of Physics Carnegie Mellon University 5000 Forbes Ave PittsburghPA15213 United States Department of Physics University of California Santa Barbara Santa BarbaraCA93106 United States 950 N Cherry Ave TucsonAZ85726 United States Institute of Optics and Electronics Chinese Academy of Sciences Chengdu610209 China

High-cadence, multiwavelength observations have continuously revealed the diversity of tidal disruption events (TDEs), thus greatly advancing our knowledge and understanding of TDEs. In this work, we conducted an intensive optical-UV and X-ray follow-up campaign of TDE AT2023lli, and found a remarkable month-long bump in its UV/optical light curve nearly two months prior to maximum brightness. The bump represents the longest separation time from the main peak among known TDEs to date. The main UV/optical outburst declines as t−4.10, making it one of the fastest decaying optically selected TDEs. Furthermore, we detected sporadic X-ray emission 30 days after the UV/optical peak, accompanied by a reduction in the period of inactivity. It is proposed that the UV/optical bump could be caused by the self-intersection of the stream debris, whereas the primary peak is generated by the reprocessed emission of the accretion process. In addition, our results suggest that episodic X-ray radiation during the initial phase of decline may be due to the patched obscurer surrounding the accretion disk, a phenomenon associated with the inhomogeneous reprocessing process. The double TDE scenario, in which two stars are disrupted in sequence, is also a possible explanation for producing the observed early bump and main peak. We anticipate that the multicolor light curves of TDEs, especially in the very early stages, and the underlying physics can be better understood in the near future with the assistance of dedicated surveys such as the deep high-cadence survey of the 2.5-meter Wide Field Survey Telescope (WFST). © 2024, CC BY.

关键词： Luminance

Mass-accreting white dwarfs and type Ia supernovae

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Research in Astronomy and Astrophysics 2018年第5期18卷 1-28页

作者： Bo Wang Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy ofSciences Kunming 650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China

Type Ia supernovae（SNe Ia） play a prominent role in understanding the evolution of the Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs（CO WDs） in binaries, although the mass donors of the accreting WDs are still not well determined. In this article, I review recent studies on mass-accreting WDs, including H-and He-accreting WDs. I also review currently most studied progenitor models of SNe Ia, i.e., the single-degenerate model（including the WD＋MS channel, the WD＋RG channel and the WD＋He star channel）, the doubledegenerate model（including the violent merger scenario） and the sub-Chandrasekhar mass *** progress on these progenitor models is discussed, including the initial parameter space for producing SNe Ia, the binary evolutionary paths to SNe Ia, the progenitor candidates for SNe Ia, the possible surviving companion stars of SNe Ia, some observational constraints, etc. Some other potential progenitor models of SNe Ia are also summarized, including the hybrid CONe WD model, the core-degenerate model, the double WD collision model, the spin-up/spin-down model and the model of WDs near black holes. To date, it seems that two or more progenitor models are needed to explain the observed diversity among SNe Ia.

关键词： supernovae general - binaries close - stars evolution - white dwarfs

A highly mutually-inclined, compact warm-Jupiter system KOI-984 ?

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arXiv 2021年

作者： Sun, Leilei Ioannidis, Panagiotis Gu, Shenghong Schmitt, Jürgen H.M.M. Wang, Xiaobin Kouwenhoven, M.B.N. Perdelwitz, Volker Dotti, Francesco Flammini Czesla, Stefan Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Hamburger Sternwarte Universität Hamburg Gojenbergsweg 112 Hamburg21029 Germany School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China 111 Renai Rd. Suzhou Dushu Lake Science and Education Innovation District Suzhou Industrial Park Suzhou215123 China Department of Physics Ariel University Ariel40700 Israel

The discovery of a population of close-orbiting giant planets (≤ 1 au) has raised a number of questions about their origins and dynamical histories. These issues have still not yet been fully resolved, despite over 20 years of exoplanet detections and a large number of discovered exoplanets. In particular, it is unclear whether warm Jupiters (WJs) form in situ, or whether they migrate from further outside and are even currently migrating to form hot Jupiters (HJs). Here, we report the possible discovery and characterization of the planets in a highly mutually-inclined (Imut 45◦), compact two-planet system (KOI-984), in which the newly discovered warm Jupiter KOI-984c is on a 21.5-day, moderately eccentric (e 0.4) orbit, in addition to a previously known 4.3-day planet candidate KOI-984b. Meanwhile, the orbital configuration of a moderately inclined (Imut 15◦), low-mass (mc 24M⊕;Pb 8.6 days) perturbing planet near 1:2 mean motion resonace with KOI-984b could also well reproduce observed transit timing variations and transit duration variations of KOI-984b. Such an eccentric WJ with a close-in sibling would pose a challenge to the proposed formation and migration mechanisms of WJs, if the first scenario is supported with more evidences in near future;this system with several other well-measured inclined WJ systems (e.g., Kepler-419 and Kepler-108) may provide additional clues for the origin and dynamical histories of WJs. Copyright © 2021, The Authors. All rights reserved.

关键词： Extrasolar planets

Formation of millisecond pulsars with helium white dwarfs, ultra-compact X-ray binaries and gravitational wave sources

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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

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

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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

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

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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

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.

关键词：

An explanation for 13 consecutive days activities of Mrk 421

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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

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