Supermassive recoil velocities for binary black-hole mergers with antialigned spins

Abstract

Recent calculations of the recoil velocity in binary black hole mergers have found the kick velocity to be of the order of a few hundred km/s in the case of non-spinning binaries and about $500 $km/s in the case of spinning configurations, and have lead to predictions of a maximum kick of up to $1300 $km/s. We test these predictions and demonstrate that kick velocities of at least $2500 $km/s are possible for equal-mass binaries with anti-aligned spins in the orbital plane. Kicks of that magnitude are likely to have significant repercussions for models of black-hole formation, the population of intergalactic black holes and the structure of host galaxies.