Circumbinary Disk Accretion into Spinning Black Hole Binaries

• Published in: The Astrophysical journal Vol. 913; no. 1; pp. 16 - 32
• Main Authors: Lopez Armengol, Federico G., Combi, Luciano, Campanelli, Manuela, Noble, Scott C., Krolik, Julian H., Bowen, Dennis B., Avara, Mark J., Mewes, Vassilios, Nakano, Hiroyuki
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center The American Astronomical Society 19.05.2021; American Astronomical Society / IOP Publishing; IOP Publishing
• Subjects: Accretion; Accretion disks; Angular momentum; Astronomy; ASTRONOMY AND ASTROPHYSICS; Astrophysics; Black holes; Fluid flow; Interstellar gas; Magnetohydrodynamic simulation; Magnetohydrodynamical simulations; Relativistic effects; Rotating black holes; Simulation; Supermassive black holes; Agn; Gravitational Waves; Grmhd; Supermassive Binary Black Hole; Multi-Messenger Astrophysics; Lisa
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.3847/1538-4357/abf0af

Supermassive black hole binaries are likely to accrete interstellar gas through a circumbinary disk. Shortly before merger, the inner portions of this circumbinary disk are subject to general relativistic effects. To study this regime, we approximate the spacetime metric of close orbiting black holes by superimposing two boosted Kerr–Schild terms. After demonstrating the quality of this approximation, we carry out very long-term general relativistic magnetohydrodynamic simulations of the circumbinary disk. We consider black holes with spin dimensionless parameters of magnitude 0.9, in one simulation parallel to the orbital angular momentum of the binary, but in another anti-parallel. These are contrasted with spinless simulations. We find that, for a fixed surface mass density in the inner circumbinary disk, aligned spins of this magnitude approximately reduce the mass accretion rate by 14% and counter-aligned spins increase it by 45%, leaving many other disk properties unchanged.