Simulations of the progenitors of black hole-neutron star gravitational wave sources

TL;DR

This paper presents the first detailed 1D stellar evolution simulations of over 30 black hole-neutron star progenitors, providing insights into their formation and potential to produce gravitational wave events.

Contribution

It offers a comprehensive, self-consistent modeling of BH+NS progenitors from post-common envelope binaries to core collapse, filling a gap in stellar evolution literature.

Findings

Identified potential progenitors for GW200115-like events.

Demonstrated the evolution of BH+NS systems with stable mass transfer.

Linked specific systems to observed X-ray binaries like SS433.

Abstract

Recent discoveries of gravitational wave (GW) events most likely originating from black hole (BH) + neutron star (NS) mergers reveal the existence of BH+NS binaries. The formation of BH+NS binaries and their merger rates through isolated binary evolution have been investigated extensively with population synthesis simulations. A detailed stellar evolution modelings of the formation of this population, however, is missing in the literature. In this work, we perform the first complete 1D model of more than 30 BH+NS progenitor systems which are calculated self-consistently until the iron core collapse with infall velocity exceeds 1000 km s^-1. Focusing on the progenitors of BH- NS GW sources, we apply the MESA code starting from a post-common envelope binary with short orbital period (< 1 day) consisting of a BH and a zero-age main-sequence helium star that experiences stable mass transfer. These NS masses could be significantly larger depending on the exact mass cut during the supernova explosion. These BH+NS systems are likely to merge and produce GW events within a Hubble time. System C is a potential progenitor of a GW200115-like event, while Systems A and B are possible candidates for a GW200105-like event and may represent the final destiny of the X-ray binary SS433.