Metallicity-constrained merger rates of binary black holes and the   stochastic gravitational wave background
  The recent detection of the binary black hole merger GW150914 demonstrates the existence of black holes more massive than previously observed in X-ray binaries in our Galaxy. This article explores different scenarios of black hole formation in the context of self-consistent cosmic chemical evolution models that simultaneously match observations of the cosmic star formation rate, optical depth to reionization and metallicity of the interstellar medium. This framework is used to calculate the mass distribution of merging black hole binaries and its evolution with redshift. We also study the implications of the black hole mass distribution for the stochastic gravitational wave background from mergers and from core collapse events. 
Irina Dvorkin, Elisabeth Vangioni, Joseph Silk, Jean-Philippe Uzan,   Keith A. Olive
astro-ph.HE astro-ph.CO astro-ph.GA gr-qc