在本文中，我们估算了遥远潮汐瓦解事件（TDE）候选体 Swift J2058.4+0516 的中心黑洞（BH）质量，该事件是与 TDE 相关的相对论性喷流诞生的第二个候选体。在文献中，通过不同的间接方法估算出的 Swift J2058.4+0516 的黑洞质量差异很大。因此，通过另一种独立方法来确定 Swift J2058.4+0516 的中心黑洞质量是必要且有趣的。在此，基于用于描述 Swift J2058.4+0516 长期时间依赖性 X 射线变率的理论 TDE 模型，在仔细考虑了与 TDE 紧密相关的相对论性喷流所暗示的内在聚束效应后，中心黑洞质量可以被很好地确定为约 $1.05_{-0.29}^{+0.39}\times10^5{\rm M_\odot}$。此外，Swift J2058.4+0516 在已报道的 TDE 候选体的黑洞质量与能量转移效率空间中是一个独特的天体，为探测和/或预测相对论性 TDE 候选体以产生相对论性喷流提供了有趣的线索。
英文摘要：
In the manuscript, central black hole (BH) mass is estimated in the distant TDE (tidal disruption event) of {\it Swift} J2058.4+0516 as the second candidate of relativistic jet birth related to TDE. {\it Swift} J2058.4+0516 have quite different BH masses estimated through different indirect methods in the literature. Therefore, it is necessary and interesting to determine the central BH mass in {\it Swift} J2058.4+0516 by one another independent method. Here, based on the theoretical TDE model applied to describe the long-term time-dependent X-ray variabilities of {\it Swift} J2058.4+0516, the central BH mass can be well determined to be around $1.05_{-0.29}^{+0.39}\times10^5{\rm M_\odot}$, after kind considerations of suggested intrinsic beaming effects from such relativistic jet tightly related to TDE. Moreover, the {\it Swift} J2058.4+0516 is an unique object in the space of BH masses versus energy transfer efficiencies of the reported TDE candidates, providing interesting clues to detect and/or anticipate candidates of relativistic TDE to make the birth of relativistic jets.
SWIFT J164449.3+573451: a plunging event with the Poynting-flux dominated outflow
Swift J164449+573451是一个奇特的爆发，很可能是由一个巨大的黑洞对恒星的潮汐破坏提供动力。在潮汐破坏的情况下，我们表明，近星点的距离是相当小的破坏半径和外流应主要通过磁活动（例如，Blandford-Znajek过程），否则不能再现满足关系式$L_{X}\propto\dot{M}$的X射线余辉发射，其中$L_{X}$是X射线光度，$\dot{M}$是吸积率。我们还认为，$L_{X}\propto\dot{M}$可能存在于伽马射线暴的快速衰减阶段。
A model for the multiwavelength radiation from tidal disruption event Swift J1644+57
由雨燕卫星探测到的恒星潮汐破裂事件的伽马射线观测以及无线电、毫米波、红外线和X射线波段的后续观测提供了丰富的数据集，可用于研究大质量黑洞的吸积、相对论喷流的产生及其与周围介质的相互作用。TDE Swift J1644+57的射电和X射线数据提供了一个关于该事件中产生的相对论性喷流能量的相互矛盾的图像：X射线数据表明喷流能量随时间t^{-5/3}下降，而射电和毫米波段持续约100天的几乎平坦的光变曲线被解释为总能量输出随时间增加的证据。我们在这项工作中表明，平坦的光变曲线不需要增加能量来减速外部冲击（其通过同步加速器过程产生无线电和毫米辐射），相反，平坦行为是由于通过X射线光子流过外部冲击的电子的逆康普顿冷却;较早时间的较高X射线通量更快速地冷却电子从而减少出射的同步加速器通量，并且随着x射线通量随时间下降，这种效应会减弱。
We report on the X-ray properties of the new transient Swift J0840.7$-$3516, discovered with Swift/BAT in 2020 February, using extensive data of Swift, MAXI, NICER, and NuSTAR. The source flux increased for $\sim 10^3$ s after the discovery, decayed rapidly over $\sim$ 5 orders of magnitude in 5 days, and then remained almost constant over 9 months. Large-amplitude short-term variations on time scales of 1--$10^4$ s were observed throughout the decay. In the initial flux rise, the source showed a hard power-law shaped spectrum with a photon index of $\sim 1.0$ extending up to $\sim 30$ keV, ab…
Tidal disruption events (TDEs) occur when a star passes close enough to a galaxy's supermassive black hole to be disrupted by tidal forces. We discuss new observations of IGRJ12580+0134, a TDE observed in NGC 4845 (d=17 Mpc) in November 2010, with the Karl G. Jansky Very Large Array (JVLA). We also discuss a reanalysis of 2010-2011 Swift and XMM-Newton observations, as well as new, late-time Swift observations. Our JVLA observations show a decay of the nuclear radio flux until 2015, when a plateau was seen, and then a significant (~factor 3) radio flare during 2016. The 2016 radio flare was al…
We present continued radio and X-ray observations of the previously relativistic tidal disruption event (TDE) Swift J164449.3+573451 (\sw) extending to about 9.4 years post disruption, as part of ongoing campaigns with the Jansky Very Large Array (VLA) and the \textit{Chandra} X-ray observatory. We find that the X-ray emission has faded below detectable levels, with an upper limit of $\lesssim 3.5\times 10^{-15}$ erg cm$^{-2}$ s$^{-1}$ in a 100 ks observation, while the radio emission continues to be detected and steadily fade. Both are consistent with forward shock emission from a non-relativ…
Temporal Variation of the Coronal Radius Parameter in a Jetted Tidal Disruption Event: Swift J1644+57
University of Manitoba（曼尼托巴大学）；Chungbuk National University（忠北国立大学）；Aoyama Gakuin University（青山学院大学）；Physical Research Laboratory（物理研究实验室）；Indian Centre for Space Physics（印度空间物理中心）；Indian Institute of Astrophysics（印度天体物理研究所）；INAF-IASF Palermo（意大利国家天体物理研究所巴勒莫天体物理研究所）；University of British Columbia（不列颠哥伦比亚大学）；SRM University-AP（SRM大学安得拉邦校区）
We explore the temporal structure of tidal disruption events pointing out the corresponding transitions in the lightcurves of the thermal accretion disk and of the jet emerging from such events. The hydrodynamic time scale of the disrupted star is the minimal time scale of building up the accretion disk and the jet and it sets a limit on the rise time. This suggest that Swift J1644+57, that shows several flares with a rise time as short as a few hundred seconds could not have arisen from a tidal disruption of a main sequence star whose hydrodynamic time is a few hours. The disrupted object mus…
Tidal disruption events are an excellent probe for supermassive black holes in distant inactive galaxies because they show bright multi-wavelength flares lasting several months to years. AT2019dsg presents the first potential association with neutrino emission from such an explosive event.
Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. II. The Relativistic Jet Shuts Off and a Transition to Forward Shock X-ray/Radio Emission
Radio Monitoring of the Tidal Disruption Event Swift J164449.3+573451. I. Jet Energetics and the Pristine Parsec-Scale Environment of a Supermassive Black Hole
Odd Radio Circles or ORCs are recently discovered edge-brightened, low surface brightness circular radio sources. The progenitors and astrophysical processes responsible for their origins are presently debated. Some ORCs are host-less and some appear to be hosted in distant quiescent galaxies. Two plausible explanations consider ORCs as nearby supernova remnants with sizes a few hundred parsec in the intragroup medium of the local group of galaxies or alternatively shocked halos of a few hundred kpc extent around distant galaxies. The input shock energy required to create ORCs of a few hundred…
We report a candidate tidal disruption event (TDE) found in the Zwicky Transient Facility (ZTF) survey data. This candidate, with its transient name AT2021acak, showed brightness increases of $\sim$1\,mag around MJD~59500 and subsequent power-law--like brightness declines. We have conducted multiple optical spectroscopic observations with the 2.4-m Lijiang telescope and one observation at X-ray and ultraviolet (UV) bands with the {\it Neil Gehrels Swift Observatory (Swift)}. The optical spectra of the source show broad H and He emission line and Fe emission features. Possible 0.3--2\,keV X-ray…
We present the discovery of a luminous X-ray transient, serendipitously detected by Swift's X-ray Telescope (XRT) on 2020 February 5, located in the nucleus of the galaxy SDSS J143359.16+400636.0 at z=0.099 (luminosity distance $D_{\rm L}=456$ Mpc). The transient was observed to reach a peak luminosity of $\sim10^{44}$ erg s$^{-1}$ in the 0.3--10 keV X-ray band, which was $\sim20$ times more than the peak optical/UV luminosity. Optical, UV, and X-ray lightcurves from the Zwicky Transient Facility (ZTF) and Swift show a decline in flux from the source consistent with $t^{-5/3}$, and observation…
Tidal disruption of a neutron star near naked singularity
Charotar University of Science and Technology（查科塔尔科学与技术大学）；Ahmedabad University（艾哈迈达巴德大学）；Tata Institute of Fundamental Research（塔塔基础研究所）；Massachusetts Institute of Technology（麻省理工学院）
The short-term X-ray variability of tidal disruption events (TDEs) and its similarities with active galactic nuclei (AGN) are poorly understood. In this work, we show the diversity of TDE's short-term X-ray variability, and take Swift J1644+57 as an example to study the evolution of various properties related to the short-term X-ray variability, such as the X-ray flux distribution, power spectral density (PSD), rms variability, time lag and coherence spectra. We find that the flux distribution of Swift J1644+57 has a lognormal form in the normal state, but deviates from it significantly in the…
When a star passes close to a supermassive black hole (BH), the BH's tidal forces rip it apart into a thin stream, leading to a tidal disruption event (TDE). In this work, we study the post-disruption phase of TDEs in general relativistic hydrodynamics (GRHD) using our GPU-accelerated code H-AMR. We carry out the first grid-based simulation of a deep-penetration TDE ($β$=7) with realistic system parameters: a black-hole-to-star mass ratio of $10^6$, a parabolic stellar trajectory, and a nonzero BH spin. We also carry out a simulation of a tilted TDE whose stellar orbit is inclined relative to …
IGR J12580+0134: A Possible Repeated Partial Tidal Disruption Event Inferred from Late-Time Radio Re-brightenin
Huazhong University of Science and Technology（华中科技大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；University of Science and Technology of China（中国科学技术大学）
