Binary Black Hole Formation and Mergings

TL;DR

This paper investigates the formation, evolution, and merging rates of binary black holes using modern stellar evolution models, considering supernova kicks, and predicts their detectability by gravitational wave observatories.

Contribution

It introduces a model for binary black hole formation incorporating supernova kicks and predicts merger rates and properties relevant for gravitational wave detection.

Findings

Binary black holes merge within the Hubble time with non-zero supernova kicks.

Calculated galactic merging rates of binary BH systems.

Predicted distributions of orbital eccentricities and spin-orbit angles.

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.