Evidence from high mass X-ray binaries that Galactic WR components of WR+O binaries end their life with a supernova explosion

TL;DR

This paper provides evidence that Wolf-Rayet stars in high mass X-ray binaries likely end their lives with supernova explosions that impart significant kicks, based on population predictions and observed data.

Contribution

It offers new evidence supporting the idea that WR stars in binaries undergo supernovae with natal kicks, influencing the population of observed BH X-ray binaries.

Findings

Predicted many more wind-fed BH HMXBs if WR stars collapse with zero kick.

Observed only one such system (Cyg X-1), indicating high natal kicks.

Supports the hypothesis that WR stars end as supernovae with kicks.

Abstract

Theoretical population number studies of binaries with at least one black hole (BH) component are obviously depending on whether or not BHs receive a (natal) kick during their formation. Several observational facts seem to indicate that indeed BHs receive a kick during their formation. In the present paper we discuss additional evidence. The progenitors of wind fed high mass X-ray binaries (HMXB) with a BH component (BH HMXB) are WR+OB binaries where the Wolf-Rayet (WR) star will finally collapse and form the BH. Starting from the observed population of WR+OB binaries in the Solar Neighborhood we predict the population of wind fed BH HMXBs as a function of the BH-natal kick. The simulations reveal that when WR stars collapse into a BH with zero or low kick, we would expect 100 or more wind fed BH HMXBs in the Solar Neighborhood whereas only one is observed (Cyg X-1). We consider this as evidence that either WR components in binaries end their life as a neutron star or that they collapse into BHs both accompanied by a supernova explosion imparting significant (natal) kicks.