Maximum speed of hypervelocity stars ejected from binaries

TL;DR

This paper investigates the maximum velocities of hypervelocity stars ejected from binaries disrupted by asymmetric supernovae, finding that such a mechanism can explain most G/K-dwarf HVSs but not all B-type HVSs.

Contribution

It provides a detailed analysis of the maximum velocities achievable for HVSs from binary disruptions, highlighting the limitations of this scenario for B-type stars.

Findings

HVSs up to ~770 km/s from B-star binaries

HVSs up to ~1280 km/s from G/K-dwarf binaries

Binary disruption can explain most G/K-dwarf HVSs, but not all B-type HVSs

Abstract

The recent detection of hypervelocity stars (HVSs) as late-type B-stars and HVS candidate G/K-dwarfs raises the important question of their origin. In this Letter, we investigate the maximum possible velocities of such HVSs if they are produced from binaries which are disrupted via an asymmetric supernova explosion. We find that HVSs up to ~770 and ~1280 km/s are possible in the Galactic rest frame from this scenario for these two subclasses of HVSs, respectively. We conclude that whereas a binary origin cannot easily explain all of the observed velocities of B-type HVSs (in agreement with their proposed central massive black hole origin) it can indeed account for the far majority (if not all) of the recently detected G/K-dwarf HVS candidates.