Detecting floating black holes as they traverse the gas disk of the
  Milky Way
  A population of intermediate-mass black holes (BHs) is predicted to be freely
floating in the Milky Way (MW) halo, due to gravitational wave recoil, ejection
from triple BH systems, or tidal stripping in the dwarf galaxies that merged to
make the MW. As these BHs traverse the gaseous MW disk, a bow shock forms,
producing detectable radio and mm/sub-mm synchrotron emission from accelerated
electrons. We calculate the synchrotron flux to be $\sim \rm 0.01-10\, mJy$ at
GHz frequency, detectable by Jansky Very Large Array, and $\sim 10-100\,\mu\rm
Jy$ at $\sim10^{10}-10^{12} \,\rm Hz$ frequencies, detectable by Atacama Large
Millimeter/sub-millimter Array. The discovery of the floating BH population
will provide insights on the formation and merger history of the MW as well as
on the evolution of massive BHs in the early Universe.
