The outflow efficiency (eta) from black hole (BH) accretion disc systems is known to depend upon both the BH spin (a) and the amount of large-scale magnetic flux threading the BH and disc. Semi-analytical flux-trapping models suggest retrograde BHs should trap much more large-scale magnetic flux near the BH leading to much higher eta than for prograde BHs. We self-consistently determine the amount of large-scale magnetic flux trapped by rapidly spinning (a = -0.9 and 0.9) BHs using global 3D time-dependent non-radiative general relativistic magnetohydrodynamic simulations of thick (h/r ~ 0.3-0.6) discs. We find that BH-trapped flux builds up until it is strong enough to disrupt the inner accretion disc. Contrary to prior flux-trapping models, which do not include the back-reaction of magnetic flux on the disc, our simulations show prograde BHs trap more magnetic flux, leading to about 3 times higher eta than retrograde BHs for |a| = 0.9. Both spin orientations can produce highly efficient jets, eta ~ 100%, with increasing eta for increasing disc thickness. The similarity of eta for prograde and retrograde BHs makes it challenging to infer the sign of BH spin based on jet energetics alone.
Is there a retrograde accretion disk around 4U 1626$-$67? Tracking torque reversals with a state-space model
University of Melbourne（墨尔本大学）；Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav)（澳大利亚研究理事会引力波发现卓越中心）；University of Massachusetts Lowell（马萨诸塞大学洛厄尔分校）；California Institute of Technology（加州理工学院）
Electromagnetic Emission and Orbital Evolution of Eccentric Supermassive Black Hole Binaries in Retrograde Disks
Institute of Science and Technology Austria (ISTA)（奥地利科学技术研究院）；Niels Bohr International Academy, Niels Bohr Institute（尼尔斯·玻尔国际学院，尼尔斯·玻尔研究所）；Space Telescope Science Institute（太空望远镜科学研究所）；Johns Hopkins University（约翰斯·霍普金斯大学）；Columbia University（哥伦比亚大学）；New York University（纽约大学）
McFACTS II: Mass Ratio--Effective Spin Relationship of Black Hole Mergers in the AGN Channel
New Mexico State University（新墨西哥州立大学）；Center for Computational Astrophysics, Flatiron Institute（计算天体物理中心，平顿研究所）；Department of Astrophysics, American Museum of Natural History（美国自然历史博物馆天体物理学系）；Department of Science, BMCC, City University of New York（纽约市立学院科学系，纽约市立大学）；Graduate Center, City University of New York（纽约市立大学研究生中心）；Gravitational Astrophysics Laboratory, NASA Goddard Space Flight Center（引力天体物理学实验室，NASA戈达德太空飞行中心）；Center for Computational Relativity and Gravitation, Rochester Institute of Technology（计算相对论与引力中心，罗切斯特理工学院）
QPEs from Warped Disk Collisions with EMRIs: Brightness-Recurrence Diagram and Gravitational-Wave Follow-up
Wuhan University（武汉大学）；Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家航空航天技术研究委员会-国家航空技术研究所）；University of Science and Technology of China（中国科学技术大学）；Tsung-Dao Lee Institute, Shanghai Jiao-Tong University（上海交大李政道研究所）；Shanghai Jiao-Tong University（上海交通大学）
