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Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
Abstract:
We present results on the mass, spin, and redshift distributions of the ten
binary black hole mergers detected in the first and second observing runs
completed by Advanced LIGO and Advanced Virgo. We constrain properties of the
binary black hole (BBH) mass spectrum using models with a range of
parameterizations of the BBH mass and spin distributions. We find that the mass
distribution of the more massive black hole in such binaries is well
approximated by models with no more than 1% of black holes more massive than
$45 M{}_{\odot}$, and a power law index of $\alpha = {{1.6}^{+1.5}_{-1.7}}$
(90% credibility). We also show that BBHs are unlikely to be composed of black
holes with large spins aligned to the orbital angular momentum. Modelling the
evolution of the BBH merger rate with redshift, we show that it is flat or
increasing with redshift with $88$% probability. Marginalizing over
uncertainties in the BBH population, we find robust estimates of the BBH merger
rate density of $R = {{53.2}^{+58.5}_{-28.8}}$ Gpc$^{-3}$ yr$^{-1}$ (90%
credibility). As the BBH catalog grows in future observing runs, we expect that
uncertainties in the population model parameters will shrink, potentially
providing insights into the formation of black holes via supernovae, binary
interactions of massive stars, stellar cluster dynamics, and the formation
history of black holes across cosmic time.