• DOI:10.1103/PhysRevLett.116.201301
• Corpus ID: 23710177

Did LIGO Detect Dark Matter?

@article{Bird2016DidLD,
  title={Did LIGO Detect Dark Matter?},
  author={Simeon Bird and Ilias Cholis and Julian B. Mu{\~n}oz and Yacine Ali-Ha{\"i}moud and Marc Kamionkowski and Ely D. Kovetz and Alvise Raccanelli and Adam G. Riess},
  journal={Physical review letters},
  year={2016},
  volume={116 20},
  pages={
          201301
        }
}

• S. Bird, I. Cholis, +5 authors A. Riess
• Published 1 March 2016
• Physics
• Physical review letters

We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains a window for masses 20M_{⊙}≲M_{bh}≲100M_{⊙} where primordial black holes (PBHs) may constitute the dark matter. If two BHs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. The bound BHs will rapidly spiral inward due to the emission of gravitational radiation and ultimately will merge. Uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. Still, reasonable estimates span a range that overlaps the 2-53  Gpc^{-3} yr^{-1} rate estimated from GW150914, thus raising the possibility that LIGO has detected PBH dark matter. PBH mergers are likely to be distributed spatially more like dark matter than luminous matter and have neither optical nor neutrino counterparts. They may be distinguished from mergers of BHs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. Next-generation experiments will be invaluable in performing these tests.