Young Star Clusters Dominate the Production of Detached Black Hole-Star Binaries

Understand

The recent discovery of two detached black hole-star (BH-star) binaries from Gaia's third data release has sparkled interest in understanding the formation mechanisms of these systems.

• We investigate the formation of these systems by dynamical processes in young open star clusters (SCs) and via isolated binary (IB) evolution, using a combination of direct $N$-body models and population synthesis simulations.
• By comparing dynamical and isolated systems created using the same model of binary stellar evolution, we find that dynamical formation in SCs is nearly 40 times as efficient per unit of star formation at producing BH-star binaries compared to IB evolution.
• We expand this analysis to the full Milky Way (MW) using a FIRE-2 hydrodynamical simulation of a MW-mass galaxy.