SCYON Abstract

Received on May 08 2006

The effect of mass-segregation on gravitational wave sources near massive black holes

AuthorsClovis Hopman and Tal Alexander
Faculty of Physics, Weizmann Institute of Science, POB 26, Rehovot 76100, Israel
Accepted byAstrophysical Journal Letters


Gravitational waves (GWs) from the inspiral of compact remnants (CRs) into massive black holes (MBHs) will be observable to cosmological distances. While a CR spirals in, 2-body scattering by field stars may cause it to fall into the MBH before reaching a short period orbit that would give an observable signal. As a result, only CRs very near (~0.01 pc) the MBH can spiral in successfully. In a multi-mass stellar population, the heaviest objects sink to the center, where they are more likely to slowly spiral into the MBH without being swallowed prematurely. We study how mass-segregation modifies the stellar distribution and the rate of GW events. We find that the inspiral rate per galaxy for white dwarfs is 30 Gyr-1, for neutron stars 6 Gyr-1, and for 10 M(sun) stellar black holes (SBHs) 250 Gyr-1. The high rate for SBHs is due to their extremely steep density profile, nBH (r) ∝ r-2. The GW detection rate will be dominated by SBHs.