Paper: astro-ph/0512123
Date: Mon, 5 Dec 2005 20:41:27 GMT (913kb)

Title: The Role of Primordial Kicks on Black Hole Merger Rates

Authors: Miroslav Micic, Tom Abel and Steinn Sigurdsson

Comments: 12 pages, 9 figures, submitted to MNRAS

Journal-ref: proceedings of 22nd Texas Symposium on Relativistic Astrophysics,
Stanford University, December 13-17, 2004
\\
Primordial stars are likely to be very massive $\geq30\Msun$, form in
isolation, and will likely leave black holes as remnants in the centers of
their host dark matter halos in the mass range
$10^{6}-10^{10}\Ms$. Such early black holes, at redshifts z$\gtsim10$, could
be the seed black holes for the many supermassive black holes found in galaxies
in the local universe. If they exist, their mergers with nearby supermassive
black holes may be a prime signal for long wavelength gravitational wave
detectors. We simulate formation of black holes in the center of high redshift
dark matter halos and explore implications of initial natal kick velocities
conjectured by some formation models. The central concentration of early black
holes in present day galaxies is reduced if they are born even with moderate
kicks of tens of km/s. The modest kicks allow the black holes to leave their
parent halo, which consequently leads to dynamical friction being less
effective on the lower mass black holes as compared to those still embedded in
their parent halos. Therefore, merger rates may be reduced by more than an
order of magnitude. Using analytical and illustrative cosmological N--body
simulations we quantify the role of natal kicks of black holes formed from
massive metal free stars on their merger rates with supermassive black holes in
present day galaxies. Our results also apply to black holes ejected by the
gravitational slingshot mechanism.

\\ ( http://arXiv.org/abs/astro-ph/0512123 , 913kb)