Hydrodynamic Natal Kicks and Formation of Black Hole Binaries

Abstract

The observation of over 300 Gravitational Wave (GW) events by the LIGO-Virgo-KAGRA collaboration, has yielded information of the merger of compact object binaries, such as their individual masses and spins. However, the effective spin parameter obtained from the GW signal provides important information that could be used to discern the binary's formation channel. Overall, binaries formed from dynamic interactions in dense stellar environments are expected to have a random distribution of effective spins between -1 and 1. Meanwhile, binaries formed from the evolution of isolated stellar binaries are expected to have positive effective spins unless there is a large enough natal kick during the compact object formation that could significantly alter the orientation of the individual spins with respect to the binary's angular momentum. We study the viability of obtaining large natal kicks during the formation of massive Black Holes by studying the asymmetric mild explosion of $13\text{M}_{\odot}$, $21\text{M}_{\odot}$, $28\text{M}_{\odot}$ and $34\text{M}_{\odot}$ pre-supernova stellar models, by means of 3D Smooth Particle Hydrodynamics simulations. Our results show that, even kicks in the order of $\sim$ 1000 km/s, which are among the highest values observed for natal kicks, can't consistently change the orientation of the orbit. Physical setups where the orientation of the orbit changes require the kick to be directed correctly, and they would also require for the supernova explosion energy to be quite high.