paper

Rapid onset of a Comptonisation zone in the repeating tidal disruption event XMMSL2 J140446.9-251135

arXiv:2510.02905 · doi:10.1051/0004-6361/202554193

Abstract

We report here on observations of a tidal disruption event, XMMSL2 J1404-2511, discovered in an XMM-Newton slew, in a quiescent galaxy at z=0.043. X-ray monitoring covered the epoch when the accretion disc transitioned from a thermal state, with kT~80 eV, to a harder state dominated by a warm, optically-thick corona. The bulk of the coronal formation took place within 7 days and was coincident with a temporary drop in the emitted radiation by a factor 4. After a plateau phase of ~100 days, the X-ray flux of XMMSL2 J1404-2511 decayed by a factor 500 within 230 days. We estimate the black hole mass in the galaxy to be solar masses and the peak X-ray luminosity ergs/s. The optical/UV light curve is flat over the timescale of the observations with ergs/s. We find that TDEs with coronae are more often found in an X-ray sample than in an optically-selected sample. Late-time monitoring of the optical sample is needed to test whether this is an intrinsic property of TDEs or is due to a selection effect. From the fast decay of the X-ray emission we consider that the event was likely due to the partial stripping of an evolved star rather than a full stellar disruption, an idea supported by the detection of two further re-brightening episodes, two and four years after the first event, in the SRG/eROSITA all-sky survey.

16 pages, 5 figures. Accepted for publication in A&A

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