Gravitational waves from primordial black holes and new weak scale phenomena

We entertain the possibility that primordial black holes of mass ∼(1026–1029) g, with Schwarzschild radii of O(cm), constitute ∼10% or more of cosmic dark matter, as allowed by various constraints. These black holes would typically originate from cosmological eras corresponding to temperatures O(10–100) GeV, and may be associated with first order phase transitions in the visible or hidden sectors. In case these small primordial black holes get captured in orbits around neutron stars or astrophysical black holes in our galactic neighborhood, gravitational waves from the resulting “David and Goliath (D&G)” binaries could be detectable at Advanced LIGO or Advanced Virgo for hours or more, possibly over distances of O(10) Mpc encompassing the Local Supercluster of galaxies. The proposed Einstein Telescope would further expand the reach for these signals. A positive signal could be further corroborated by the discovery of new particles in the O(10–100) GeV mass range, and potentially also the detection of long wavelength gravitational waves originating from the first order phase transition era.