Determining the progenitors of merging black-hole binaries
  We investigate a possible method for determining the progenitors of black
hole (BH) mergers observed via their gravitational wave (GW) signal. We argue
that measurements of the cross-correlation of the GW events with overlapping
galaxy catalogs may provide an additional tool in determining if BH mergers
trace the stellar mass of the Universe, as would be expected from mergers of
the endpoints of stellar evolution. If on the other hand the BHs are of
primordial origin, as has been recently suggested, their merging would be
preferentially hosted by lower biased objects, and thus have a lower
cross-correlation with luminous galaxies. Here we forecast the expected
precision of the cross-correlation measurement for current and future GW
detectors such as LIGO and the Einstein Telescope. We then predict how well
these instruments can distinguish the model that identifies high-mass BH-BH
mergers as the merger of primordial black holes that constitute the dark matter
in the Universe from more traditional astrophysical sources.
