On energetics and progenitors of Odd Radio Circles: A causal connection with tidal disruption of stars?

TL;DR

This paper proposes that the energy from multiple tidal disruption events around black holes can explain the origins of Odd Radio Circles, linking them to galaxy mergers and post-starburst galaxy hosts.

Contribution

It introduces a novel energetic mechanism involving tidal disruption events as a plausible origin for ORCs, connecting them to galaxy mergers and specific host galaxy types.

Findings

Cumulative energy from tidal disruptions can match ORC energies.

Post-starburst galaxies are likely hosts for ORCs.

Tidal disruption events are more common in post-starburst galaxies.

Abstract

Odd Radio Circles or ORCs are recently discovered edge-brightened, low surface brightness circular radio sources. The progenitors and astrophysical processes responsible for their origins are presently debated. Some ORCs are host-less and some appear to be hosted in distant quiescent galaxies. Two plausible explanations consider ORCs as nearby supernova remnants with sizes a few hundred parsec in the intragroup medium of the local group of galaxies or alternatively shocked halos of a few hundred kpc extent around distant galaxies. The input shock energy required to create ORCs of a few hundred kpc size is estimated in a range of $10^{55} - 10^{59}$ erg. It is shown here that the cumulative energy in unbound debris ejected from multiple ($10^{5} - 10^{9}$) tidal disruption events over $\sim100$ Myr period around a central massive black hole can meet the required energies to generate ORCs around some galaxies, which have recently undergone a merger. The potential hosts for ORCs are identified here as abundant post-starburst galaxies at intermediate redshifts having massive black holes. A causal connection between ORC around quiescent galaxies and tidal disruption may find support in the observed dominance of tidal disruption events in post-starburst galaxies.