Inferring Binary-Black-Hole Formation Channels in Third-Generation Gravitational-Wave Detectors

Future gravitational-wave (GW) detector-network will detect binary-black-hole mergers (BBHs) up to redshift of ~10, which provides a direct measurement of the formation history of BBHs. Here we show how GW detections of BBHs made by proposed third-generation detectors can be used to infer the formation channels of BBHs. To distinguish between the two main expected formation channels-- dynamical formation or binary stellar evolution--we parametrize the redshift distribution predicted by cosmological simulation in each channel and infer their branching ratio and characteristic parameters. With one month of observations at the predicted rate of ~15000 BBHs per month, parameters describing the volumetric merger rate can be constrained at the few percent level.