RADIATIVELY INEFFICIENT ACCRETION FLOWS INDUCED BY GRAVITATIONAL-WAVE EMISSION BEFORE MASSIVE BLACK HOLE COALESCENCE

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/726/1/L14· OSTI ID:21560584

Hayasaki, Kimitake ^[1]

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1. Department of Astronomy, Kyoto University Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan)

We study an accretion flow during the gravitational-wave driven evolution of binary massive black holes. After the binary orbit decays due to an interaction with a massive circumbinary disk, the binary is decoupled from the circumbinary disk because the orbital-decay timescale due to emission of gravitational wave becomes shorter than the viscous timescale evaluated at the inner edge of circumbinary disk. During the subsequent evolution, the accretion disk, which is truncated at the tidal radius because of the tidal torque, also shrinks as the orbital decay. Assuming that the disk mass changed by this process is all accreted, the disk becomes radiatively inefficient when the semimajor axis is several hundred Schwarzschild radii. The high-energy radiations, in spite of a low bolometric luminosity, are emitted from an accretion disk around each black hole long before the black hole coalescence, as well as the gravitational wave signals. The synchrotron process can notably produce potentially observable radio emissions at large distances if there is a strong magnetic field with an equipartition value. By the addition of the assumption of a dipole magnetic field, step-like light variations are seen in the observed light curve because the luminosity is higher and its duration time is shorter in the radio emission by the disk around the secondary black hole than that of the primary black hole. Such a precursor would be unique to not a single black hole system but a binary black hole system, and implies that binary black holes finally merge without accretion disks.

• OSTI ID: 21560584
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 726; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
COALESCENCE
COSMIC RADIO SOURCES
DECAY
DIAGRAMS
ELECTROMAGNETIC RADIATION
EMISSION
EVOLUTION
GALAXIES
GRAVITATIONAL WAVES
INFORMATION
LUMINOSITY
OPTICAL PROPERTIES
ORBITS
PHYSICAL PROPERTIES
QUASARS
RADIATIONS
RADIOWAVE RADIATION
SCHWARZSCHILD RADIUS
VISIBLE RADIATION