Binary Black Hole Formation and Mergings

Abstract

The formation and evolution of binary black holes (BH) is studied using the modern evolutionary scenario for very massive stars with high mass loss (Vanbeveren et al. 1998). Main sequence stars with masses $M>35 M_\odot$ are assumed to form a BH in the end of their nuclear evolution. The mass of BH formed is parametrized as $M_{bh}=k_{bh}\times M_{SN}$, where $M_{SN}$ is the mass of the pre-supernova star taken from evolutionary calculations, $k_{bh}\le 1$. The possibility is explored that a newly formed BH acquires a kick velocity 0-250 km/s. Binary BH are found to merge within the Hubble time at an appreciable rate only for non-zero kick velocities. We calculate the galactic merging rates of binary BH systems, their detection rate by the initial laser interferometers, and the distributions of merging binary BH over orbital eccentricities at different frequencies. The distribution of angles between BH spins and the orbital angular momentum is also presented.