Dark Matter Gravity Waves at LIGO and LISA
  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
10Hz and otherwise more sensitive than LIGO. The LISA detector, expected to
come online in 2034, will be useful at frequencies below 1Hz but a second
space-based detector beyond LISA, sensitive up to 10Hz, will be necessary fully
to study dark matter.
