Rapid Merger of Binary Primordial Black Holes: an Implication for GW150914

Understand

We propose a new scenario for the evolution of a binary of primordial black holes (PBHs).

• We consider a dynamical friction by ambient dark matter, scattering of dark matter particles with a highly eccentric orbit besides the standard two-body relaxation process to refill the loss cone, and interaction between the binary and a circumbinary disk, assuming that PBHs do not constitute the bulk of dark matter.
• Binary PBHs lose the energy and angular momentum by these processes, which could be sufficiently efficient for a typical configuration.
• Such a binary coalesces due to the gravitational wave emission in a time scale much shorter than the age of the universe.