We study the merger rate of dark matter PIMBHs (Primordial Intermediate Mass Black Holes). We conclude that the black holes observed by LIGO in GW150914 and later events were probably not dark matter PIMBHs but rather the result of gravitational collapse of very massive stars. To study the PIMBHs by gravitational radiation will require a detector sensitive to frequencies below 10 Hz and otherwise more sensitive than LIGO. The LISA detector, expected to come online in 2034, will be useful at frequencies below 1 Hz but further gravitational wave detectors beyond LISA, sensitive up to 10 Hz, and higher strain sensitivity will be necessary to fully study dark matter.
Relic gravity waves and 7 keV dark matter from a GeV scale inflaton