The coalescence of a binary black hole can be accompanied by a large gravitational recoil due to anisotropic emission of gravitational waves. A recoiling supermassive black hole (SBH) can subsequently undergo long-lived oscillations in the potential well of its host galaxy, suggesting that offset SBHs may be common in the cores of massive ellipticals. We have analyzed HST archival images of 14 nearby core ellipticals, finding evidence for small ($\lesssim 10$ pc) displacements between the AGN (locating the SBH) and the center of the galaxy (the mean photocenter) in 10 of them. Excluding objects that may be affected by large-scale isophotal asymmetries, we consider six galaxies to have detected displacements, including M87, where a displacement was previously reported by Batcheldor et al. 2010. In individual objects, these displacements can be attributed to residual gravitational recoil oscillations following a major or minor merger within the last few Gyr. For plausible merger rates, however, there is a high probability of larger displacements than those observed, if SBH coalescence took place in these galaxies. Remarkably, the AGN-photocenter displacements are approximately aligned with the radio source axis in four of the six galaxies with displacements, including three of the four having relatively powerful kpc-scale jets. This suggests intrinsic asymmetries in radio jet power as a possible displacement mechanism, although approximate alignments are also expected for gravitational recoil. Orbital motion in SBH binaries and interactions with massive perturbers can produce the observed displacement amplitudes but do not offer a ready explanation for the alignments.
A Large Systematic Search for Close Supermassive Binary and Rapidly Recoiling Black Holes - II. Continued Spectroscopic Monitoring and Optical Flux Variability
A recoiling supermassive black hole in a powerful quasar
Space Telescope Science Institute for the European Space Agency (ESA), ESA Office（欧洲空间局（ESA）太空望远镜科学研究所，ESA办公室）；The William H. Miller III Department of Physics & Astronomy, Johns Hopkins University（约翰斯·霍普金斯大学威廉·H·米勒三世物理与天文学系）；IPAC, California Institute of Technology（加州理工学院 IPAC）；Dipartimento di Fisica "G. Occhialini'', Università degli Studi di Milano-Bicocca（米兰比可卡大学 G. Occhialini 物理系）；INFN, Sezione di Milano-Bicocca（意大利国家核物理研究所米兰比可卡分部）；Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre（罗马第三大学数学与物理系）；INAF - Osservatorio Astrofisico di Torino（意大利国家天体物理研究所都灵天文台）；INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚天体物理与空间科学观测站）；Institute of Astronomy, Graduate School of Science, the University of Tokyo（东京大学大学院理学研究科天文学系）；Astronomy Data Center, National Astronomical Observatory of Japan（日本国立天文台天文数据中心）；NASA-Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；Department of Physics, University of Maryland, Baltimore County（马里兰大学巴尔的摩分校物理系）；Advanced Technology Center, National Astronomical Observatory of Japan（日本国立天文台先进技术中心）；Space Telescope Science Institute（太空望远镜科学研究所）；Dept. of Astronomy, University of Maryland, College Park（马里兰大学学院公园分校天文学系）
Recoiling Black Hole Candidates from Spatially Offset Broad Emission Lines in MaNGA
University of Colorado Boulder（科罗拉多大学博尔德分校）；Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder（科罗拉多大学环境科学研究合作研究所）；The University of Memphis（孟菲斯大学）
The Supermassive Black Hole in the Nearby Spiral Galaxy M81: A Robust Mass from JWST/NIRSpec Stellar Dynamics
University of Michigan（密歇根大学）；Vietnam National University – Ho Chi Minh City（越南国立大学胡志明市）；University of Oxford（牛津大学）；International University, Vietnam National University in Ho Chi Minh City（越南国立大学胡志明市国际大学）
The MEGaN project II. Gravitational waves from intermediate mass- and binary black holes around a supermassive black hole
本文研究了大质量星团群沉积在超大质量黑洞附近的中等质量黑洞、恒星黑洞和双星黑洞的演化。恒星黑洞在SMBH周围迅速分离，形成极端质量比的吸气，并以$Γ= 0.02-0.2$ yr $^{-1}$ Gpc $^{-3}$的速率在红移$z=0$处合并。一些围绕SMBH运行的IMBH有利于在哈勃时间内合并的大质量对的形成，这是该通道$Γ=0.03$ yr $^{-1}$ Gpc $^{-3}$的合并率。合并后的反冲可以将残余物从星系中心喷射出去，特别是在矮星系中。我们的研究结果表明，这种机制可以导致高达$10^5$喷射SMBH在1 Gpc。IMBH与同一簇中的几个单一和二元BH共存可以显著影响它们的演化，要么驱动二元破坏，产生中等质量比的吸气（合并率$Γ=9.5$ yr $^{-1}$ Gpc $^{-3}$），要么促进BHB聚结（$Γ=2-8$ yr $^{-1}$ Gpc $^{-3}$）。在一些模拟中，SMBH促进BHB聚结，导致该过程的合并速率为$Γ=1$ yr $^{-1}$ Gpc $^{-3}$。我们注意到，在星系核中经历合并的BHB可能被错误地估计为比实际重的$\sim 30\%$，这是因为SMBH周围的快速运动引起的波频率的多普勒频移。我们所有的模拟都是使用$N$体代码进行的，该代码专门用于处理近距离接触和后牛顿动力学，其中还包括粒子运动方程中的星系场和动力学摩擦。
Chandra X-ray Observations of Quasars with Velocity-Offset Broad Lines: Assessing the Binary Supermassive Black Hole Hypothesis
Binghamton University（宾汉姆顿大学）；The Pennsylvania State University（宾夕法尼亚州立大学）；Georgia Institute of Technology（佐治亚理工学院）；West Virginia University（西弗吉尼亚大学）；Canadian Institute for Advanced Research（加拿大高级研究院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
Targeted search for eccentric supermassive binary black holes in OJ 287 and nearby galaxy clusters with PPTA DR3
Institute for Frontier in Astronomy and Astrophysics & Faculty of Arts and Sciences, Beijing Normal University（北京师范大学前沿天文与天体物理研究所及文理学院）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理研究所（爱因斯坦研究所））；Leibniz Universität Hannover（汉诺威莱布尼茨大学）；School of Physics and Astronomy, Monash University（蒙纳士大学物理与天文学院）；ARC Centre for Excellence for Gravitational Wave Discovery (OzGrav)（ARC引力波发现卓越中心（OzGrav））；Australia Telescope National Facility, CSIRO, Space & Astronomy（澳大利亚望远镜国家设施，CSIRO空间与天文部）；School of Physics, University of Melbourne（墨尔本大学物理学院）；Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin–Milwaukee（威斯康星大学密尔沃基分校物理系引力、宇宙学与天体物理中心）
Searching for Nearby Supermassive Black Hole Binaries with GRAVITY
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Cité（巴黎天文台 LESIA，巴黎文理研究大学，法国国家科学研究中心，索邦大学，巴黎西岱大学）；Faculdade de Engenharia, Universidade do Porto（波尔图大学工程学院）；CENTRA - Centro de Astrofísica e Gravitação, IST, Universidade de Lisboa（里斯本大学理工学院 CENTRA 天体物理与引力中心）；European Southern Observatory（欧洲南方天文台）；Univ. Grenoble Alpes, CNRS, IPAG（格勒诺布尔阿尔卑斯大学，法国国家科学研究中心，IPAG）；Max-Planck-Institut für extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；Max-Planck-Institut für Astronomie (MPIA)（马克斯·普朗克天文学研究所）；INAF - Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理研究所）；Institute of Astronomy, KU Leuven（鲁汶大学天文学研究所）
Accretion rates and radiative efficiencies of Sagittarius A* and nearby supermassive black holes estimated using empirical relations: Implications for accretion models
Predicting Potential Host Galaxies of Supermassive Black Hole Binaries Based on Stellar Kinematics in Archival IFU Surveys
Bishop’s University（主教大学）；Trottier Space Institute and Department of Physics, McGill University（麦吉尔大学特鲁蒂尔太空研究所和物理系）；California Institute of Technology（加州理工学院）；Vanderbilt University（范德堡大学）
