The origin of progenitors in merging black hole binaries

Are the stellar-mass merging binary black holes, recently detected by their gravitational wave signal, of stellar or primordial origin? Answering this question will have profound implications for our understanding of the Universe, including the nature of dark matter, the early Universe and stellar evolution. We develop the idea that the clustering properties of merging binary black holes can provide information about binary formation mechanisms and origin, in particular the cross-correlation of galaxy with gravitational wave catalogues carries information about whether black hole mergers trace more closely the distribution of dark matter - indicative of primordial origin - or that of stars harboured in luminous and massive galaxies - indicative of a stellar origin. We forecast the detectability of such signal for several forthcoming and future gravitational wave interferometers and galaxy surveys. Our results show that forthcoming experiments could allow us to test most of the parameter space of the still viable models investigated, and shed more light on the issue of binary black hole origin and evolution.