Qingjuan Yu
This is an invited commentary on the Nobel Prize in Physics 2020 which was awarded to Roger Penrose "for the discovery that black hole formation is a robust prediction of the general theory of relativity," and Reinhard Genzel and Andrea Ghez "for the discovery of a supermassive compact object at the center of our galaxy."
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Supermassive Black Hole Binaries: The Search Continues
引力束缚超大质量黑洞双星被认为是星系合并和宇宙大尺度结构生长的自然产物。然而，它们仍然难以观测，因此提出了一个问题，与这些系统相关的特征观测签名。在这次会议上，我讨论了目前的理论认识和观测搜索SBHB的最新进展和前景。
Active galactic nuclei (AGN) host some of the most energetic phenomena in the Universe. AGN are thought to be powered by accretion of matter onto a rotating disk that surrounds a supermassive black hole. Jet streams can be boosted in energy near the event horizon of the black hole and then flow outward along the rotation axis of the disk. The mechanism that forms such a jet and guides it over scales from a few light-days up to millions of light-years remains uncertain, but magnetic fields are thought to play a critical role. Using the Atacama large mm/submm array (ALMA), we have detected a pol…
The evolution of main sequence binaries that reside in the Galactic Centre can be heavily influenced by the central supermassive black hole (SMBH). Due to these perturbative effects, the stellar binaries in dense environments are likely to experience mergers, collisions or ejections through secular and/or non-secular interactions. More direct interactions with the central SMBH are thought to produce hypervelocity stars (HVSs) and tidal disruption events (TDEs). In this paper, we use N-body simulations to study the dynamics of stellar binaries orbiting a central SMBH primary with an outer SMBH …
Multi-messenger approaches to binary supermassive black holes in the "continuous-wave" regime
脉冲星计时阵列对轨道间距<< 1pc的超大质量黑洞（SMBH）双星的引力波十分敏感。目前，这类系统的观测资料很少，尽管它们是研究星系演化、合并动力学和活跃核形成的核心人物。我们回顾了通过电磁辐射过程探测SMBH双星的前景，这些过程被认为与星系合并和后期双星演化有关。然后，我们讨论了这些系统的联合脉冲星定时和电磁研究的科学目标，包括促进二进制参数估计，确定星系主机的引力波发射器，并合并动力学和宇宙学的相关研究。使用即将到来的高精度定时阵列与国际脉冲星定时阵列和平方公里阵列，结合正在进行的电磁观测活动，以确定活跃的SMBH双星，在不久的将来为多信使天体物理学提供了大量的可能性。
Blazar PG 1553+113 is thought to be a host of supermassive black hole binary (SMBHB) system. A 2.2-year quasi-periodicity in the $γ$-ray light curve was detected, possibly result of jet precession. Motivated by the previous studies based on the $γ$-ray data, we analyzed the X-ray light curve and spectra observed during 2012--2020. The 2.2-year quasi-periodicity might be consistent with the main-flare recurrence in the X-ray light curve. When a weak rebrightening in the $γ$-ray was observed, a corresponding relatively strong brightening in the X-ray light curve can be identified. The "harder-wh…
Testing the Association of Supermassive Black Hole Infrared Flares and High-energy Neutrinos
研究通过分析NEOWISE和IceCat-1数据，发现近距吸积闪焰与高能中微子信号无显著关联，挑战了此前的结论。
A strong magnetic field around the supermassive black hole at the centre of the Galaxy
我们银河系的中心拥有最接近超大质量黑洞的候选者。该来源被认为是由来自其环境的辐射效率低下的气体积累提供动力。这种形式的吸积是大多数星系核能量供应的标准模式。X射线测量已经分辨出了一种稀薄的热气成分，它可以从这种成分中产生。然而，气体的磁化强度，决定吸积流结构的一个关键参数，仍然未知。强磁场可以影响吸积的动力学，从下落的气体中去除角动量，通过相对论喷流排出物质，并导致观察到的同步辐射。在这里，我们报告多频测量与几个新发现的脉冲星靠近银河系中心的射电望远镜，并显示其异常大的法拉第旋转表明一个动态相关的磁场附近的黑洞。如果这个磁场被吸积到事件视界，它提供了足够的磁通量来解释观测到的从黑洞发射的从无线电到X射线的辐射。
Dark Matter Constraints from the Eccentric Supermassive Black Hole Binary OJ 287
本文利用偏心超大质量双黑洞 OJ 287 的耀发计时数据，通过广义相对论计算约束主黑洞周围可能存在的暗物质尖峰质量，发现其质量小于主黑洞质量的 3%。
Evolution of supermassive stars as a pathway to black hole formation
超大质量恒星的质量超过一百万个太阳质量，可能是星系核中超大质量黑洞的祖先。由于它们的核燃烧时间尺度很短，只有当物质能够以超过~ 1太阳质量/年的速度积累时，这些物体才能形成。在这里，我们重新审视旋转稳定的超大质量恒星的结构和演化，考虑到它们不断积累的质量和热弛豫。我们表明，超大质量恒星的外层在恒星的主序星寿命的大部分时间里都没有热松弛。因此，它们不像以前文献中假设的n=3多变体，而是由对流（多变）核心组成，周围是包含大部分质量的对流稳定包络。我们计算了这些包层的结构，其中比熵与包层质量M（R）的2/3次方成正比。通过匹配的信封解决方案对流核心，我们计算的核心质量作为时间的函数。我们估计了最初的黑洞质量形成的核心崩溃的结果，以及他们随后的增长，通过吸积从膨胀的信封（“准恒星”）的结果。以这种方式形成的种子黑洞的典型质量可能在10^4-10^5太阳质量之间，比第三星族恒星消亡后留下的残余物要大得多。因此，超大质量黑洞可能是在一个比Pop III恒星形成时期晚得多的快速坍缩时期形成的。
Spoon-Feeding Giant Stars to Supermassive Black Holes: Episodic Mass Transfer from Evolving Stars and Their Contribution to the Quiescent Activity of Galactic Nuclei
如果恒星在单一轨道上过于靠近超大质量黑洞（SMBH），它们可能会被潮汐扰乱。潮汐破裂事件被认为是发光但短暂的吸积事件的动力，这些事件可以在瞬态耀斑中点亮原本静止的SMBH。在这里，我们探讨了一个更渐进的潮汐剥离的过程中，恒星接近潮汐破坏半径的恒星演化，而在偏心轨道。在质量转移开始后，这些恒星在每一次近心点通过时都将质量转移到SMBH，从而产生在轨道时间尺度上重复的低水平耀斑。特别是巨恒星，会对质量损失做出失控的反应，并在数十到数百个轨道周期内将物质“勺式”喂入黑洞。与完整的潮汐扰动事件相反，对于质量大于约1000万太阳质量的黑洞，这种馈送模式的占空比是统一的。这种准稳态SMBH馈送模式与通过恒星风间接SMBH馈送的模式具有竞争力，并且勺状馈送巨星可能在确定本地SMBH的静态光度方面发挥重要作用。
Relativistic Jets and Winds in Radio-Identified Supermassive Black Hole Binary Candidates
该研究提出了一种可推广的喷流模型，解释了超大质量黑洞双星候选体的喷流和光变现象，并预测了射电偏振、成像和发射线变化，以指导未来的观测研究。
Elusive supermassive black hole binaries (SMBHBs) are thought to be the penultimate stage of galaxy mergers, preceding a final coalescence phase. SMBHBs are sources of continuous gravitational waves, possibly detectable by pulsar timing arrays; the identification of candidates could help in performing targeted gravitational wave searches. Due to their origin in the innermost parts of active galactic nuclei (AGN), X-rays are a promising tool to unveil the presence of SMBHBs, by means of either double Fe K$α$ emission lines or periodicity in their light curve. Here we report on a new method to s…
Identifying Host Galaxies of Supermassive Black Hole Binaries Found by PTAs
本文提出宿主星系识别流程，通过模拟PTA数据恢复单源引力波信号并量化定位区域与候选星系数量，评估不同条件下筛选后的宿主候选数目及其影响因素。
Disks of gas accreting onto supermassive black holes are thought to power active galactic nuclei (AGN). Stars may form in gravitationally unstable regions of these disks, or may be captured from nuclear star clusters. Because of the dense gas environment, the evolution of such embedded stars can diverge dramatically from those in the interstellar medium. This work extends previous studies of stellar evolution in AGN disks by exploring a variety of ways that accretion onto stars in AGN disks may differ from Bondi accretion. We find that tidal effects from the supermassive black hole significant…
Disruption of a Red Giant Star by a Supermassive Black Hole and the Case of PS1-10jh
新一代潮汐扰动理论模型的开发是及时的，因为在对瞬变天空的调查中捕获了越来越多的不同事件。最近，Gezari等人报告了一类新的潮汐破裂事件的发现：富含氦的恒星核心的破裂，被认为是红巨星（RG）的残余。出于这一发现和其他人的预期，我们认为潮汐相互作用的RG星与超大质量黑洞（SMBH），导致剥离的恒星信封和随后的inspiral的紧凑的核心走向黑洞。一旦恒星外壳被移除，核心的内旋就受到潮汐加热和引力辐射的驱动，直到核心落入SMBH或被潮汐破坏。在潮汐破裂候选PS1- 10 jh的情况下，我们发现，有一组轨道解在高偏心率，潮汐剥离的氢信封吸积的SMBH之前，氦核心被破坏。这将RG核心的参数空间的一部分，强大的潮汐加热可以解除简并的紧凑的残留物和破坏它之前，它达到潮汐半径。我们考虑如何解释这一系列的事件令人困惑的情况下，从PS1- 10 jh的光谱的氢发射线，并引起其其他观测功能。
The remnants of binary black hole mergers can be given recoil kick velocities up to $5,000\text{ km s$^{-1}$}$ due to anisotropic emission of gravitational waves. E1821+643 is a recoiling supermassive black hole moving at $\sim 2,100\text{ km s$^{-1}$}$ along the line-of-sight relative to its host galaxy. This suggests a recoil kick of $\sim 2,240\text{ km s$^{-1}$}$. Such a kick is powerful enough to eject E1821+643 from its $M_\text{gal}\sim 2 \times 10^{12}\text{ M}_{\odot}$ host galaxy. In this work, we address the question: what are the likely properties of the progenitor binary that form…
Could the neutrino emission of TXS 0506+056 come from the accretion flow of the supermassive black hole?
该研究探讨了TXS 0506+056的中微子辐射是否来自超大质量黑洞的吸积流，通过磁重联或湍流加速质子，并考虑MAD和SANE两种吸积状态，发现超爱丁顿吸积可解释中微子耀发，亚爱丁顿吸积可解释稳态通量。
The properties of the first continuous gravitational waves: Optimizing pulsar timing observations for supermassive black hole binary detection
本文探究首批可分辨超大质量黑洞双星的性质，优化脉冲星计时观测策略可提升其探测概率，高频次观测更易识别高频双星，相关系统可通过光学巡天开展电磁后续观测。
Synchrotron polarization signatures of surface waves in supermassive black hole jets
本文通过全局GRMHD模拟磁捕获盘，发现黑洞附近持续发射的波在喷流与风的剪切层传播并改变磁场结构，偏振辐射转移计算表明这些波会降低偏振度，其特征有望被下一代事件视界望远镜观测。
Wind-fed Supermassive Black Hole Accretion in the Ultracompact Dwarf Galaxy M60-UCD1
研究通过模拟发现M60-UCD1的X射线辐射源于由恒星风驱动的弱吸积超大质量黑洞。
Testing a scale-independent method to measure the mass of black holes
估算星系中心的黑洞质量不仅是理解吸积物理的基础，而且也是研究星系宇宙演化的基础。最近，一种仅基于X射线数据的新方法被成功地应用于确定银河系中的黑洞质量。由于X射线被认为是通过恒星和超大质量黑洞中的康普顿化过程产生的，原则上，相同的方法可以应用于估计超大质量黑洞的质量。在这项工作中，我们测试这一假设进行了系统的分析样本的活动星系核，其黑洞质量已经确定通过混响映射，并拥有高品质的XMM-牛顿档案数据。这种新的缩放技术和混响映射值得到的黑洞质量之间的良好协议表明，这种方法是强大的，同样适用于恒星和超大质量黑洞，使之成为一个真正的尺度无关的技术黑洞的测定。
A Parameter Study of the Electromagnetic Signatures of an Analytical Mini-Disk Model for Supermassive Binary Black Hole Systems
本文通过解析迷你吸积盘模型结合广义相对论光线追踪，系统研究了超大质量双黑洞系统电磁信号对黑洞自旋、质量比、吸积率、视角和初始间距的依赖，并评估了快光近似的适用性。
Mergers of galaxies are thought to cause significant gas inflows to the inner parsecs, which can activate rapid accretion onto supermassive black holes (SMBHs), giving rise to Active Galactic Nuclei (AGN). During a significant fraction of this process, SMBHs are predicted to be enshrouded by gas and dust. Studying 52 galactic nuclei in infrared-selected local Luminous and Ultra-luminous infrared galaxies in different merger stages in the hard X-ray band, where radiation is less affected by absorption, we find that the amount of material around SMBHs increases during the last phases of the merg…
Supermassive black hole (BH) binaries are thought to produce self-lensing flares (SLF) when the two BHs are aligned with the line-of-sight. If the binary orbit is observed nearly edge-on, we find a distinct feature in the light curve imprinted by the BH shadow from the lensed BH. We study this feature by ray-tracing in a binary model and predict that 1\% of the current binary candidates could show this feature. Our BH tomography method proposed here could make it possible to extract BH shadows that are spatially unresolvable by high-resolution VLBI.
The Tidal Disruption of Giant Stars and Their Contribution to the Flaring Supermassive Black Hole Population
类太阳恒星被认为经常被星系核内的超大质量黑洞（SMBH）破坏。然而，随着恒星从主序星演化出来，它们对潮汐破裂的脆弱性急剧增加，因为它们发展出一个由致密的核心和纤细的外壳组成的分叉结构。在这里，我们提出了第一个流体动力学模拟的巨大恒星的潮汐破裂，并表明，核心有一个重大的影响，恒星的生存能力的遭遇。具有更大质量核心的恒星即使在深度碰撞中也保留了大部分的包层质量。由巨星分裂产生的吸积耀斑应该会持续数十至数百年。它们在瞬时搜索中的特征信号不是通常与潮汐破坏事件相关的$t^{-5/3}$衰减，而是在数月至数年的时间尺度上亮度的许多数量级的相关上升。我们计算不同的演化阶段的恒星在典型的银河系中心的相对中断率，然后使用我们的结果产生预期的耀斑事件人口的蒙特卡罗实现。我们发现，人口统计的潮汐破裂耀斑是强烈依赖于恒星和黑洞的质量，特别是接近极限SMBH质量尺度的$\sim 10^8 M_\odot$。在这个黑洞质量，我们预测一个急剧的转变，在SMBH耀斑饮食超出所有可观察到的中断产生的演化恒星，伴随着一个戏剧性的截止在整体潮汐中断耀斑率。质量小于这个极限质量尺度的黑洞将显示来自主序星和演化恒星的可观测耀斑，其中巨星贡献了高达10%的事件率。在不同演化状态下被破坏的恒星的相对比例可以限制我们星系核以外的其他星系核中恒星的性质和分布。
Recurring flares from supermassive black hole binaries: implications for tidal disruption candidates and OJ 287
我讨论的可能性，吸积超大质量黑洞（SMBH）的二进制文件与子秒差距的分离周期性地重复发光爆发，中断相对平静的时期。这一假设的动机是由嵌入进积盘中的双星模拟中通常发现的两个特征：（i）在双星周围形成一个中心的低密度空腔，以及（ii）气体泄漏到这个空腔中，每个轨道发生一次通过近径向轨迹上的离散流。第一个特征将减少系统相对于由单个SMBH供电的活动星系核的紧急光学/UV通量，而第二个特征可以触发光度的准周期波动。我认为，准周期吸积签名可能比以前认为的更戏剧性，因为下落的气体流可以强烈冲击热通过自碰撞和潮汐压缩，从而提高粘性吸积。任何光学上厚的气体，如果围绕着两个SMBH中的任何一个旋转，都可以在下一对气流沉积之前吸积，从而为每个轨道上重复出现的短暂的发光耀斑提供燃料。由于吸积事件之间的流量减少，这种腔吸积耀斑可能被误认为是恒星在静止核中的潮汐破裂。如果观测到耀斑的准周期重现，或者如果它们是由非常大质量的SMBH产生的，而SMBH不能破坏太阳型恒星，那么耀斑就可以与潮汐破坏事件区分开来。它们可能在LSST或eROSITA等调查中偶然发现。我提出了一个启发式的玩具模型作为概念证明的生产空腔吸积耀斑，并产生模拟光变曲线和specta。我也适用于活跃的星系OJ 287，其生产的准周期光学耀斑对长期以来一直助长猜测，它的主机SMBH二进制的模型。
Major galaxy mergers are thought to play an important part in fuelling the growth of supermassive black holes. However, observational support for this hypothesis is mixed, with some studies showing a correlation between merging galaxies and luminous quasars and others showing no such association. Recent observations have shown that a black hole is likely to become heavily obscured behind merger-driven gas and dust, even in the early stages of the merger, when the galaxies are well separated (5 to 40 kiloparsecs). Merger simulations further suggest that such obscuration and black-hole accretion…
Quasi-periodic oscillation (QPO) detected in the X-ray radiation of black hole X-ray binaries (BHXBs) is thought to originate from dynamical processes in the close vicinity of the black holes (BHs), and thus carries important physical information therein. Such a feature is extremely rare in active galactic nuclei (AGNs) with supermassive BHs. Here we report on the detection of a possible X-ray QPO signal with a period of 3800\,s at a confidence level $>99.99\%$ in the narrow-line Seyfert 1 galaxy (NLS1) 1H~0707-495 in one data set in 0.2-10\,keV taken with {\it XMM-Newton}. The statistical sig…
Active galactic nuclei, hosting supermassive black holes and launching relativistic jets, are the most numerous objects on the gamma-ray sky. At the other end of the mass scale, phenomena related to stellar mass black holes, in particular gamma-ray bursts and microquasars, are also seen on the gamma-ray sky. While all of them are thought to launch relativistic jets, the diversity even within each of these classes is enormous. In this review, I will discuss recent very high energy gamma-ray results that underline both the similarity of the black hole systems, as well as their diversity.
Binary supermassive black holes (BSBHs) are expected to be a generic byproduct from hierarchical galaxy formation. The final coalescence of BSBHs is thought to be the loudest gravitational wave (GW) siren, yet no confirmed BSBH is known in the GW-dominated regime. While periodic quasars have been proposed as BSBH candidates, the physical origin of the periodicity has been largely uncertain. Here we report discovery of a periodicity (P=1607$\pm$7 days) at 99.95% significance (with a global p-value of ~$10^{-3}$ accounting for the look elsewhere effect) in the optical light curves of a redshift …
The Fundamental Plane of Black Hole Activity in the Optical Band
黑洞的吸积和喷流的形成一直被认为是尺度不变的。一个表明尺度不变性的经验关系是黑洞活动的基本平面，它是由黑洞质量和射电/X射线光度给出的空间中的平面。我们使用[OIII]发射线的光度而不是X射线光度来寻找这个平面的替代版本。我们使用从帕洛玛光谱调查中选出的39个超大质量黑洞的完整样本，并提供可用的无线电和光学测量以及有关黑洞质量的信息。一个恒星质量的X射线双星样本也被包括在内，以检查吸积背后的物理过程是否在整个黑洞质量范围内具有普遍性。我们提出的AGN样本上进行多元回归分析的结果，并表明，该样本伸展作为一个平面在3D对数空间创建的辐射热光度，射电光度和黑洞质量。我们再现了X射线中黑洞活动的基本平面。我们证明，这个平面可以单独用超大质量黑洞样品得到，并且X射线双星符合所发现的关系。我们还讨论了各种低光度活动星系核的射电响度在我们的基本平面的观点。
An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10
超大质量黑洞现在被认为位于每一个有球状组成部分的巨型星系的中心，包括我们自己的银河系。然而，早期宇宙中第一个“种子”黑洞的诞生和成长在观测上是不受约束的，我们才刚刚开始拼凑它们随后演化的场景。在这里，我们报告说，附近的矮星暴星系Henize 2-10包含一个紧凑的无线电源的动态中心的星系，是空间上一致的硬X射线源。根据这些观测结果，我们得出结论，Henize 2-10拥有一个活跃的中心黑洞，质量约为100万太阳质量。这个邻近的矮星系，拥有一个巨大的黑洞和一个恒星形成的极端爆发，在许多方面类似于黑洞生长和星系质量组装早期阶段的婴儿宇宙中的星系。我们的研究结果证实了附近的恒星形成矮星系确实可以形成大质量的黑洞，这意味着它们的原始对应物也可以。此外，在Henize 2-10中缺乏一个实质性的球状组成部分，这表明超大质量黑洞的生长可能先于星系球状体的形成。
Two Peas in a Pod: The First Confirmed Dual Active Galactic Nucleus within a Green Pea Galaxy System
研究早期宇宙星系中多个超大质量黑洞增长问题，通过对绿豌豆星系系统SDSS J162209.41+352107.5观测，发现首个双活动星系核，确认其两个黑洞同时吸积，为研究星系、恒星形成与黑洞增长相互作用提供新实验室。
Astrophysical black holes are thought to be the Kerr black holes predicted by general relativity, but macroscopic deviations from the Kerr solution can be expected from a number of scenarios involving new physics. In Paper I, we studied the reflection features in NuSTAR and XMM-Newton spectra of the supermassive black hole at the center of the galaxy MCG-06-30-15 and we constrained a set of deformation parameters proposed by Konoplya, Rezzolla & Zhidenko (Phys. Rev. D93, 064015, 2016). In the present work, we analyze the X-ray data of a stellar-mass black hole within the same theoretical frame…
Reflection From the Strong Gravity Regime in a z=0.658 Gravitationally Lensed-Quasar
超大质量黑洞与其宿主星系在宇宙时间中的共同演化被编码在其自旋中。在$z>2$，超大质量黑洞被认为主要是通过合并驱动的吸积导致高自旋而生长的。然而，在$z\sim1$以下，这些黑洞是通过相干吸积还是以混沌的方式继续增长，这是未知的，尽管预测它们的自旋演化有明显的差异。测量黑洞自旋的一个既定方法是通过研究来自内吸积盘的相对论反射特征。由于它们的距离更远，迄今为止还没有在中等红移类星体中发现相对论反射特征。在这里，我们使用档案数据与一个新的，在$z=0.658$引力透镜类星体的深度观测严格检测和研究在这个中等红移类星体的反射。在这个反射光谱中存在的相对论性畸变水平使我们能够将发射限制在来自黑洞的$\lesssim3$引力半径内，这意味着在$3σ$置信水平上的自旋参数$a=0.87^{+0.08}_{-0.15} $和在$5σ$水平上的$a>0.66$。这里发现的高自旋是通过相干吸积这个黑洞的增长的指示，并建议$0.5\lesssim z \lesssim 1$之间的黑洞增长主要发生在相干吸积事件，而不是混乱。
An Over-Massive Black Hole in a Typical Star-Forming Galaxy, 2 Billion Years After the Big Bang
超大质量黑洞（SMBH）和它们的宿主星系通常被认为是共同进化的，因此SMBH在今天达到了宿主星系质量的0.2%到0.5%。从不断增长的SMBH发出的辐射预计会影响整个宿主星系的恒星形成。这种情况在早期宇宙时代的相关性尚未确定。我们目前的光谱观测的星系在红移z = 3.328，其中主机的积极吸积，极其巨大的BH，在其最后阶段的增长。SMBH的质量大约是整个宿主星系质量的十分之一，这表明它比宿主星系增长得更有效，与同步共同进化的模型相反。尽管存在SMBH驱动的气体外流，但宿主星系正在以激烈的速度形成恒星。
It is commonly assumed that in black hole accretion disks the angular momenta of the disk and the black hole are aligned. However, for a significant fraction of stellar mass black holes and supermassive black holes, the momenta may not be aligned. In such systems, the interplay of disk viscosity and general relativistic frame dragging can cause the disk to warp or break into two (or more) distinct planes; this is called the Bardeen-Petterson effect. We have developed a general relativistic ray-tracing code to find the energy spectra and polarization of warped accretion disks, accounting for th…
Tidal disruption events from a nuclear star cluster as possible origin of transient relativistic spectral lines near SMBH
讨论了休眠超大质量黑洞（SMBH）附近的潮汐破裂事件可能引起6-7 keV X射线信号中铁的光谱特征：被摧毁恒星产生的强烈闪光照射和电离的碎片中出现相对论性谱线轮廓。这可以提供确定系统参数的独特方式。我们考虑一个模型，其中核恒星星族获得扁圆形（即，一个扁平的分布），在一个超大质量黑洞附近的内部区域，而且初级辐射耀斑预计更有可能发生在赤道面附近，与下落的材料共面。这表明，初级X射线的再处理结果在一个瞬态的配置文件，应该是相关的潮汐破裂事件（TDE），否则在发光（不活跃）的星系核，即没有事先吸积盘。恒星运动的共振机制可以增加核星团中某些恒星的轨道偏心率，并有助于使它们接近潮汐半径，在那里它们可以引起TDE。提出的方案似乎是明显不同的灯柱模型的标准方案的起源的相对论性线在活动星系，其中的源被认为是主要位于对称轴附近。
The coalescence of two supermassive black holes (SMBHs) produces powerful gravitational-wave (GW) radiation and, if gas is present in the vicinity, also an electromagnetic (EM) counterpart. In the standard picture, an EM outburst will be produced when the binary "decouples" from the circum-binary disc and starts "squeezing" the disc inside the secondary orbit, resulting in its quick accretion on to the primary black hole. Here we use analytical arguments and numerical simulations to show that the disc within about $20~R_S$ of a SMBH survives the merger without being depleted. The reason is a "…
Hierarchical Black Hole Mergers in Nuclear Star Clusters: A Combined Dynamical-Secular Channel for GW231123-like Events
研究针对 GW231123 类黑洞合并事件挑战标准模型的问题，提出在核星团中通过结合双星 - 单星相互作用与中央超大质量黑洞驱动的长期演化来产生此类合并，预测相关双星并指出探测其可助于了解黑洞组装动力学。
One of the main dissipation processes acting on all scales in relativistic jets is thought to be governed by magnetic reconnection. Such dissipation processes have been studied in idealized environments, such as reconnection layers, which evolve in merging islands and lead to the production of plasmoids, ultimately resulting in efficient particle acceleration. In accretion flows onto black holes, reconnection layers can be developed and destroyed rapidly during the turbulent evolution of the flow. We present a series of two-dimensional general-relativistic magnetohydrodynamic simulations of to…
Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are thought to contain large numbers of black holes (BHs) and neutron stars (NSs), a fraction of which form binaries and could merge by Kozai-Lidov oscillations (KL). Triple compact objects are likely to be present, given what is known about the multiplicity of massive stars, whose life ends either as a NS or a BH. In this paper, we present a new possible scenario for merging BHs and NSs in galactic nuclei. We study the evolution of a triple black hole (BH) or neutron star (NS) system orbiting an SMBH in a …
The powerful jet of an off-nuclear intermediate-mass black hole in the spiral galaxy NGC 2276
吸积黑洞的喷流喷射是一种统一恒星和超大质量黑洞（SMBH）的质量不变机制，也应该适用于中等质量黑洞（IMBH），它们被认为是SMBH形成的种子。利用准同步\textit{Chandra} X射线观测和欧洲VLBI网络（EVN）射电观测，对位于星系NGC 2276一个不寻常旋臂中的$\sim$ 5 $\times$ 10 $^{4}$ M $_\odot$的离核IMBH进行了探测。IMBH，NGC 2276 - 3 c，拥有一个1.8 pc的射电喷流，其方向与大尺度（$\sim$ 650 pc）射电瓣相同，其发射与1.6 GHz和5 GHz之间的平至光学薄同步辐射一致。其喷流动能（$4 \times 10^{40}$ erg s $^{-1}$）与其辐射输出相当，喷流效率（$\geq$ 46\%）与SMBH相当。沿着喷流的$\sim$ 300 pc区域没有年轻恒星，可以提供来自IMBH的喷流反馈的观测证据。这一发现证实了吸积物理学是质量不变的，并且早期宇宙中的种子IMBH可能具有强大的喷流，这是反馈的重要来源。
The supermassive black holes (SMBHs) of narrow-line Seyfert 1 galaxies (NLS1s) are at the lowest end of mass function of active galactic nuclei (AGNs) and preferentially reside in late-type host galaxies with pseudobulges, which are thought to be formed by internal secular evolution. On the other hand, the population of radio-loud NLS1s presents a challenge for the relativistic jet paradigm that powerful radio jets are exclusively associated with very high mass SMBHs in elliptical hosts, which are built-up through galaxy mergers. We investigated distorted radio structures associated with the n…
Early on, extragalactic radio sources have pointed to a cosmologically evolving Universe. They were also an important piece of evidence for the existence of supermassive black holes, now thought to be a key component of galaxies. The observation that the power of radio sources increases with redshift, whereas the cosmological assembly of mass proceeds vice versa means that radio sources have their strongest impact in the early Universe. Our simulations suggest that radio sources heat hot halo gas, boost star formation in disc galaxies and other cold gas in the vicinity, possibly filaments, by …
Quasi-stars and the Schönberg-Chandrasekhar limit
为高红移的明亮类星体提供能量的超大质量黑洞的形成机制仍然未知。一种可能是...巨大的原星系盘的整体坍塌导致了一个准恒星的形成：一个不断增长的黑洞，最初具有典型的恒星质量，嵌入在一个流体静力学的巨型外壳中。类星是本文的主要研究对象。...在第一章中，我介绍了驱动高红移类星体的超大质量黑洞所带来的问题。...在第2章中，我概述了剑桥星的代码和修改所作的模型准星信封。在第三章中，我提出了类星的模型，其中包络的底部位于黑洞的邦迪半径。这些模型中的黑洞都有一个可靠的分数质量上限，大约是十分之一。此外，最终的黑洞质量对包络内边界半径的选择很敏感。在第4章中，我通过借鉴对流和对流主导的吸积流的工作，构建了准恒星的替代模型。这些类星的演化与第三章中描述的有质的不同。... [T]he核心黑洞不再受分数质量限制，并最终吸积其外壳中的所有物质。在第5章中，我证明了在第3章中发现的分数质量极限。在本质上与Schönberg-Schirrasekhar极限相同。分析表明…在比以前想象的更广泛的情况下存在限制。提供了一种测试，其确定复合多变体是否处于分数质量极限。在第6章中，我将这个检验应用到实际的恒星模型中，并找到证据表明分数质量极限的存在与恒星演化成红巨星有关。
Our current understanding of the curved space-time around supermassive black holes is based on actively accreting black holes, which make up only ten per cent or less of the overall population. X-ray observations of that small fraction reveal strong gravitational redshifts that indicate that many of these black holes are rapidly rotating; however, selection biases suggest that these results are not necessarily reflective of the majority of black holes in the Universe. Tidal disruption events, where a star orbiting an otherwise dormant black hole gets tidally shredded and accreted onto the blac…
Charge-starved, relativistic jets and blazar variability
耀变体的高能辐射被认为是由超大质量黑洞发射的相对论性喷流产生的。发射点必须远离空穴和相对论喷流，以避免吸收光子。在极端的情况下，辐射的快速变化表明，当喷流发射时，长度尺度小于中心黑洞引力半径的结构被印在喷流上，并在喷流被加速到高洛伦兹因子后调制所释放的辐射。我们提出了一种机制，它可以占射流的加速，并为快速变化的辐射，大振幅波的传播特性的基础上，在电荷饥饿，极性射流。使用两种流体（电子-正电子）的描述，我们发现外流表现出延迟的加速阶段，大约在1 pc开始，与波流相关的惯性变得重要。如果黑洞磁层中的电子对多重性足够小，那么发射时喷流上的时间结构会调制加速喷流产生的光子，这表明非常快速的变化仅限于黑洞磁层中电磁级联不多产的源。
Magnetically arrested accretion flows are thought to fuel some of the supermassive black holes and to power their relativistic jets. We calculate and study a time sequence of linear and circular polarimetric images of numerical, high resolution and long duration simulations of magnetically dominated flows to investigate observational signatures of strong magnetic fields near the event horizon of a non-rotating black hole. We find that the magnitude of resolved linear and circular polarizations is rather sensitive to the assumption of the coupling of electron and ions in the accretion flow. Mod…
Most massive galaxies are thought to contain a supermassive black hole in their centre surrounded by a tenuous gas environment, leading to no significant emission. In these quiescent galaxies, tidal disruption events represent a powerful detection method for the central black hole. Following the disruption, the stellar debris evolves into an elongated gas stream, which partly falls back towards the disruption site and accretes onto the black hole producing a luminous flare. Using an analytical treatment, we investigate the interaction between the debris stream and the gas environment of quiesc…
In some Seyfert Galaxies, the hard X-rays that produce fluorescent emission lines are thought to be generated in a hot corona that is compact and located at only a few gravitational radii above the supermassive black hole. We consider the possibility that this X-ray source may be powered by small scale magnetic flux tubes attached to the accretion disk near the black hole. We use three dimensional, time dependent force-free simulations in a simplified setting to study the dynamics of such flux tubes as they get continuously twisted by the central compact star/black hole. We find that, the dyna…
Resolved Magnetic-Field Structure and Variability Near the Event Horizon of Sagittarius A*
在黑洞附近，磁化吸积盘的差速旋转被认为会产生一种不稳定性，这种不稳定性会放大弱磁场，从而驱动吸积和外流。这些磁场自然会引起星系核心中观测到的同步辐射和相对论喷流的形成，但迄今为止还没有观测能够解决预期的视界尺度磁场结构。我们报告在1.3毫米波长的干涉观测，空间分辨的线性偏振辐射从银河系中心超大质量黑洞，人马座A*。我们已经发现了证据，部分有序的领域附近的事件视界，规模约6史瓦西半径，我们已经检测到并本地化的小时内变化与这些领域。
X-ray observations of black hole sources
本文回顾了X射线天文学在黑洞源研究中的发展，指出其有限的成功并强调需更灵敏的测量，重点介绍了AstroSat的CZT Imager对Cygnus X-1的最新X射线偏振测量及未来展望。
The majority of long duration ($>2$ s) gamma-ray bursts (GRBs) are believed to arise from the collapse of massive stars \cite{Hjorth+03}, with a small proportion created from the merger of compact objects. Most of these systems are likely formed via standard stellar evolution pathways. However, it has long been thought that a fraction of GRBs may instead be an outcome of dynamical interactions in dense environments, channels which could also contribute significantly to the samples of compact object mergers detected as gravitational wave sources. Here we report the case of GRB 191019A, a long G…
Ultraluminous X-ray sources are extragalactic, off-nucleus, point sources in galaxies with an X-ray luminosity above 3x10^39 erg/s, thought to be powered by accretion onto a compact object. Possible explanations include accretion onto neutron stars with strong magnetic fields, stellar-mass black holes (< 20 Msolar) at or in excess of the classical Eddington limit or intermediate-mass black holes (10^3-5 Msolar). The lack of sufficient energy resolution in previous analyses has hitherto prevented an unambiguous identification of any emission or absorption lines in the X-ray band, thereby preclu…
A Case for a Binary Black Hole System Revealed via Quasi-Periodic Outflows
研究在一个潮汐瓦解后低光度活动星系核中发现约8.3天周期的X射线吸收准周期性外流，并通过GRMHD模拟证明其可由距主黑洞约100引力半径的中等质量黑洞伴星产生，为识别中等/极端质量比双黑洞候选体提供新观测标志。
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