Mass Function of Binary Massive Black Holes in Active Galactic Nuclei
| Autor: | Yoshihiro Ueda, Naoki Isobe, Kimitake Hayasaki |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Physics
Cosmology and Nongalactic Astrophysics (astro-ph.CO) Active galactic nucleus Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Binary number Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Mass ratio Galaxy merger Orbital decay Orbital period Astrophysics - Astrophysics of Galaxies Galaxy High Energy Physics - Phenomenology General Relativity and Quantum Cosmology High Energy Physics - Phenomenology (hep-ph) Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Astrophysics::Earth and Planetary Astrophysics Circumbinary planet Astrophysics::Galaxy Astrophysics Astrophysics - Cosmology and Nongalactic Astrophysics |
| Zdroj: | Publications of the Astronomical Society of Japan. 62:1351-1360 |
| ISSN: | 2053-051X 0004-6264 |
| DOI: | 10.1093/pasj/62.5.1351 |
| Popis: | If the activity of active galactic nuclei (AGNs) is predominantly induced by major galaxy mergers, then a significant fraction of AGNs should harbor binary massive black holes in their centers. We study the mass function of binary massive black holes in nearby AGNs based on the observed AGN black-hole mass function and theory of evolution of binary massive black holes interacting with a massive circumbinary disk in the framework of coevolution of massive black holes and their host galaxies. The circumbinary disk is assumed to be steady, axisymmetric, geometrically thin, self-regulated, self-gravitating but non-fragmenting with a fraction of Eddington accretion rate, which is typically one tenth of Eddington value. The timescale of orbital decay is {then} estimated as ~10^8yr for equal mass black-hole, being independent of the black hole mass, semi-major axis, and viscosity parameter but dependent on the black-hole mass ratio, Eddington ratio, and mass-to-energy conversion efficiency. This makes it possible for any binary massive black holes to merge within a Hubble time by the binary-disk interaction. We find that (1.8+-0.6%) for the equal mass ratio and (1.6+-0.4%) for the one-tenth mass ratio of the total number of nearby AGNs have close binary massive black holes with orbital period less than ten years in their centers, detectable with on-going highly sensitive X-ray monitors such as Monitor of All-sky X-ray Image and/or Swift/Burst Alert Telescope. Assuming that all binary massive black holes have the equal mass ratio, about 20% of AGNs with black hole masses of 10^{6.5-7}M_sun has the close binaries and thus provides the best chance to detect them. Comment: 22 pages, 11 figures, accepted for publication in PASJ. The draft was significantly revised. The major differences from the previous version are as follows: (1)The circumbinary disk is assumed to be a steady, axisymmetric, geometrically thin, self-gravitating, self-regulated but non-fragmenting. (2)The stellar scattering process is taken account of in the merging process of binary black holes |
| Databáze: | OpenAIRE |
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