Estimates of black-hole natal kick velocities from observations of low-mass X-ray binaries

TL;DR

This paper reviews observational estimates of black-hole natal kicks from low-mass X-ray binaries, concluding that current data do not necessitate kicks exceeding 100 km/s, though higher velocities remain possible.

Contribution

It provides an updated analysis of black-hole birth kick velocities, focusing on the highest estimates and their implications for supernova models and binary evolution.

Findings

Current observations do not require black hole kicks over 100 km/s.

Higher kick velocities are not ruled out by existing data.

The study refines constraints on black hole natal kicks.

Abstract

The birth kicks of black holes, arising from asymmetric mass ejection or neutrino emission during core-collapse supernovae, are of great interest for both observationally constraining supernova models and population-synthesis studies of binary evolution. Recently, several efforts were undertaken to estimate black hole birth kicks from observations of black-hole low-mass X-ray binaries. We follow up on this work, specifically focussing on the highest estimated black-hole kick velocities. We find that existing observations do not require black hole birth kicks in excess of approximately 100 km/s, although higher kicks are not ruled out.