Further evidence of quasi-periodic eruptions in a tidal disruption event AT2019vcb by SRG/eROSITA

ABSTRACT We report the discovery of a short, large amplitude X-ray flare from AT2019vcb (aka Tormund), a tidal disruption event (TDE) at $z=0.088$. The discovery is based on the data from the SRG/eROSITA X-ray telescope which happened to observe the source 7 months after the onset of the optical TDE. eROSITA observation occurred 13 d after a soft flare was detected in the XMM–Newton data. Both events bear similar characteristics in terms of timing and spectral properties. eROSITA spectrum is described as an accretion disc with a characteristic temperature of ∼180 eV and luminosity $\sim 8\times 10^{43}$ erg s$^{-1}$. The eROSITA flare lasted less than 12 h and had an amplitude ≥70 with respect to the quiescent level, no flares were detected in later eROSITA observations (6–18 months later). The XMM–Newton and eROSITA flares provide strong evidence that the TDE AT2019vcb is a bona fide quasi-periodic eruption (QPE) source. Our work further strengthens the direct connection between TDEs and QPE following similar recent results in a TDE AT2019qiz.