Binary black hole mergers from Population III star clusters

Understand

Binary black holes (BBHs) born from the evolution of Population III (Pop.

• III) stars are one of the main high-redshift targets for next-generation ground-based gravitational-wave (GW) detectors.
• Their predicted initial mass function and lack of metals make them the ideal progenitors of black holes above the upper edge of the pair-instability mass gap, i.e.
• with a mass higher than $\approx{}134$ (241) M$_\odot$ for stars that become (do not become) chemically homogeneous during their evolution.