A candidate tidal disruption event in the Galaxy cluster Abell 3571

TL;DR

This paper reports the discovery and detailed analysis of a tidal disruption event in the galaxy cluster Abell 3571, observed over 13 years across multiple X-ray and optical telescopes, indicating a star was disrupted by a supermassive black hole.

Contribution

It provides the first detailed multi-year observational evidence of a tidal disruption event in a galaxy cluster, including spectral and luminosity evolution analysis.

Findings

Significant X-ray flux decay consistent with a TDE

Black body spectrum with kT ~0.12 keV during peak

Estimated energy release >2x10^50 erg over 10 years

Abstract

Tidal disruption events are possible sources of temporary nuclear activity in galactic nuclei and can be considered as good indicators of the existence of super massive black holes in the centers of galaxies. A new X-ray source has been serendipitously detected with ROSAT in a PSPC pointed observation of the galaxy cluster A3571. Given the strong flux decay of the object in subsequent detections, the tidal disruption scenario is investigated as possible explanationof the event. We followed up the evolution of the X-ray transient with ROSAT, XMM-Newton and Chandra for a total period of ~13 years. We also obtained 7-band optical/NIR photometry with GROND at the ESO/MPI 2.2m telescope. We report a very large decay of the X-ray flux of ROSAT source identified with the galaxy LEDA 095953 a member of the cluster Abell 3571. We measured a maximum 0.3-2.4 keV luminosity Log(L_X)=42.8 erg s^-1. The high state of the source lasted at least 150 ks, afterwards L_X declined as ~t^-2. The spectrum of the brightest epoch is consistent with a black body with temperature kT ~0.12 keV. The total energy released by this event in 10 yr was estimated to be Delta_E>2x10^50 erg. We interpret this event as a tidal disruption of a solar type star by the central supermassive black hole (i.e. ~10^7 M_sun) of the galaxy.