An Alternative Channel for High-mass Binary Black Holes-Dark Matter Accretion onto Black Holes

By a method of population synthesis we construct a model of dark matter (DM) accretion onto binary black holes (BHs) and investigate the merger rate of the binary BHs. We find that the merger rate can weakly increase (less than 10%). However, the DM accretion can efficiently enhance the masses of binary BHs. In our model, the result for Z = 0.01 without the DM accretion cannot explain GW170104, GW170814, and GW150914, while with the DM accretion it can cover all observations well. For the higher metallicity (Z = 0.02), our model cannot explain the mergers of high-mass binary BHs like GW170104, GW170814, and GW150914. We estimate that the merger rate of binary BHs lies between 55 and 197 Gpc−3 yr−1.