Paper: astro-ph/0511397
Date: Mon, 14 Nov 2005 15:57:33 GMT (477kb)

Title: The Galactic center welcomes black hole immigrants

Authors: Simon Portegies Zwart (UvA), Holger Baumgardt (Bonn), Stephen L. W.
McMillan (Drexel), Junichiro Makino (tokyo), Piet Hut (IAS), Toshi Ebisuzaki
(RIKEN)

Comments: 24 pages, submitted to ApJ
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We simulate the inner 100pc of the Milky-Way Galaxy to study the formation
and evolution of the population of star clusters and intermediate mass black
holes. For this study we perform extensive direct N-body simulations of the
star clusters which reside in the bulge, and of the inner few tenth of parsecs
of the super massive black hole in the Galactic center. In our N-body
simulations the dynamical friction of the star cluster in the tidal field of
the bulge are taken into account via (semi)analytic soluations. The N-body
calculations are used to calibrate a (semi)analytic model of the formation and
evolution of the bulge. We find that about 10% of the clusters born within
100pc of the Galactic center undergo core collapse during their inward
migration and form intermediate-mass black holes (IMBHs) via runaway stellar
merging. After the clusters dissolve, these IMBHs continue their inward drift,
carrying a few of the most massive stars with them. We predict that region
within about 10 parsec of the SMBH is populated by about 50IMBHs of some
1000Msun. Several of these are expected to be accompanied still by some of the
most massive stars from the star cluster. We also find that within a few
milliparsec of the SMBH there is a steady population of several IMBHs. This
population drives the merger rate between IMBHs and the SMBH at a rate of about
one per 10Myr, sufficient to build the accumulate majority of mass of the SMBH.
Mergers of IMBHs with SMBHs throughout the universe are detectable by LISA, at
a rate of about two per week.

\\ ( http://arXiv.org/abs/astro-ph/0511397 , 477kb)