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

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 $\sim 100$ 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.

5 pages, Accepted version in MNRAS Letters, Several new references added and some new analysis presented in this version

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Cited by in corpus (4)

• A unique, ring-like radio source with quadrilateral structure detected with machine learning
• Insights on the origin of ORCs from cosmological simulations
• A horseshoe-shaped ring of diffuse emission detected at 1.4 GHz
• Cosmological Zoom-In Simulation of Odd Radio Circles as Merger-Driven Shocks in Galaxy Groups