On energetics and progenitors of Odd Radio Circles
  Odd Radio Circles or ORCs are recently discovered low surface brightness
diffuse radio sources, whose progenitors and astrophysical processes
responsible for their origins are presently debated. Some ORCs appear to be
hosted in distant galaxies and some are host-less. Two plausible scenarios
consider ORCs as either nearby supernovae remnants of sizes a few hundred pc in
the intragroup medium of the local group of galaxies or alternatively shocked
halos of sizes a few hundred kpc around distant galaxies. The input energy for
shocks, required to create ORCs of a few hundred kpc size is estimated to be
$10^{56} - 10^{59}$ erg. It is shown here that the energy released in shocks
with a rate of $10^{41} - 10^{44}$ erg s$^{-1}$ due to multiple ($10^{3} -
10^{6}$) tidal disruption events in a short span of time (a few tens of Myr) in
a merger galaxy system, hosting a massive black hole can supply required energy
to generate ORCs around distant galaxies. The most plausible and abundant hosts
for ORCs can be post-starburst galaxies at intermediate redshifts. The
presently observed dominance of tidal disruption events in post-starburst
galaxies, redshift evolution and environments of post-starburst galaxies at
intermediate redshifts favourably support the current observations.
