Understanding Compact Object Formation and Natal Kicks. IV. The case of IC 10 X-1

TL;DR

This study reconstructs the evolutionary history of the X-ray binary IC 10 X-1, constraining the black hole progenitor mass, natal kick velocity, and common envelope efficiency, providing insights into massive black hole formation.

Contribution

It offers a comprehensive evolutionary model of IC 10 X-1 incorporating recent formalism, constraining progenitor mass, natal kicks, and CE efficiency without extreme assumptions.

Findings

Black hole progenitor mass > 31 solar masses

Natal kick velocity < 130 km/s

Common envelope efficiency 0.6--1

Abstract

The extragalactic X-ray binary IC 10 X-1 has attracted attention as it is possibly the host of the most massive stellar-mass black-hole (BH) known to date. Here we consider all available observational constraints and construct its evolutionary history up to the instant just before the formation of the BH. Our analysis accounts for the simplest possible history that includes three evolutionary phases: binary orbital dynamics at core collapse, common envelope (CE) evolution, and evolution of the BH--helium star binary progenitor of the observed system. We derive the complete set of constraints on the progenitor system at various evolutionary stages. Specifically: right before the core collapse event, we find the mass of the BH immediate progenitor to be > 31 Msun (at 95% of confidence, same hereafter). The magnitude of the natal kick imparted to the BH is constrained to be < 130 km/s. Furthermore, we find that the "enthalpy" formalism recently suggested by Ivanova & Chaichenets is able to explain the existence of IC 10 X-1 without the need of invoking unreasonably high CE efficiencies. With this physically motivated formalism, we find that the CE efficiency required to explain the system is in the range of 0.6--1.