Supernovae in the Central Parsec: A Mechanism for Producing Spatially Anisotropic Hypervelocity Stars

TL;DR

This study proposes that supernovae in binary systems near the Galactic center can produce hypervelocity stars with anisotropic distribution, matching observations and suggesting a link to the disc's geometry.

Contribution

It introduces a new mechanism for hypervelocity star production via supernovae in binaries, with simulations showing comparable rates to existing models and explaining observed anisotropies.

Findings

Supernovae in binaries can produce hypervelocity stars at a rate of ~2*10^-7 yr^-1.

The resulting hypervelocity stars exhibit anisotropic spatial distribution.

The mechanism aligns with observed hypervelocity star properties and distribution patterns.

Abstract

Several tens of hyper-velocity stars (HVSs) have been discovered escaping our Galaxy. These stars share a common origin in the Galactic centre and are distributed anisotropically in Galactic longitude and latitude. We examine the possibility that HVSs may be created as the result of supernovae occurring within binary systems in a disc of stars around Sgr A* over the last 100 Myr. Monte Carlo simulations show that the rate of binary disruption is ~10^-4 yr^-1, comparable to that of tidal disruption models. The supernova-induced HVS production rate (\Gamma_HVS) is significantly increased if the binaries are hardened via migration through a gaseous disc. Moderate hardening gives \Gamma_HVS ~ 2*10^-7 yr^-1 and an estimated population of ~20 HVSs in the last 100 Myr. Supernova-induced HVS production requires the internal and external orbital velocity vectors of the secondary binary component to be aligned when the binary is disrupted. This leaves an imprint of the disc geometry on the spatial distribution of the HVSs, producing a distinct anisotropy.