Two populations of LIGO-Virgo black holes
  We analyse the LIGO-Virgo data, including the recently released GWTC-2
dataset, to test a hypothesis that the data contains more than one population
of black holes. We perform a maximum likelihood analysis including a population
of astrophysical black holes with a truncated power-law mass function whose
merger rate follows from star formation rate, and a population of primordial
black holes for which we consider log-normal and critical collapse mass
functions. We find that primordial black holes alone are strongly disfavoured
by the data, while the best fit is obtained for the template combining
astrophysical and primordial merger rates. Alternatively, the data may hint
towards two different astrophysical black hole populations. We also update the
constraints on primordial black hole abundance from LIGO-Virgo observations
finding that in the $2-400 M_{\odot}$ mass range, they must comprise less than
0.2% of dark matter.
