A 200-s Quasi-Periodicity Following the Tidal Disruption of a Star by a Dormant Black Hole

TL;DR

This paper reports a 200-second quasi-periodic X-ray signal from a dormant supermassive black hole, suggesting a new method to study black hole physics and general relativity at cosmological distances.

Contribution

It presents the first detection of a quasi-periodic X-ray signal from a dormant SMBH, indicating a novel way to probe black hole properties beyond the local universe.

Findings

Detected a 200-s X-ray quasi-periodicity in a dormant SMBH

Suggests possible new method for studying black hole physics at high redshift

Opens avenues for testing general relativity beyond the local universe

Abstract

Supermassive black holes (SMBHs; $M\gtrsim10^5\msun$) are known to exist at the centre of most galaxies with sufficient stellar mass. In the local Universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, often coming in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a $\sim200$-s X-ray quasi-periodicity around a previously dormant SMBH located in the centre of a galaxy at redshift $z=0.3534$. This result may open the possibility of probing general relativity beyond our local Universe.