The effect of supernova asymmetry on coalescence rates of binary neutron stars

Abstract

We study the effect of the kick velocity -- neutron star spin alignment observed in young radio pulsars on the coalescence rate of binary neutron stars. The effect is shown to be especially strong for large kick amplitudes and tight alignments, reducing the galactic rate of binary neutron star coalescences up to an order of magnitude with respect to the rates calculated for random kicks. The spin-kick correlation also leads to much narrower NS spin-orbit misalignments compared to random kicks.