Runaway Merging of Black Holes: Analytical Constraint on the Timescale
Abstract
Following the discovery of a black hole (BH) with a mass of 103-106 Msolar in the starburst galaxy M82, we study the formation of such a BH via successive merging of stellar-mass BHs within a star cluster. The merging has a runaway characteristic. This is because massive BHs sink into the cluster core and have a high number density and because the merging probability is higher for more massive BHs. We use the Smoluchowski equation to study analytically the evolution of the BH mass distribution. Under favorable conditions, which are expected for some star clusters in starburst galaxies, the timescale of the runaway merging is on the order of at most 107 yr. This is short enough to account for the presence of a BH heavier than 103 Msolar in an ongoing starburst region.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2002
- DOI:
- 10.1086/339472
- arXiv:
- arXiv:astro-ph/0201102
- Bibcode:
- 2002ApJ...566L..17M
- Keywords:
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- Black Hole Physics;
- Galaxies: Starburst;
- Galaxies: Star Clusters;
- Astrophysics
- E-Print:
- 10 pages, no figures, to appear in The Astrophysical Journal (Letters)