Abstract for Proposal 092360

Probing the nature of eROSITA's nuclear transients

During its all-sky survey, eROSITA has uncovered a large population of transients associated with the nuclei of otherwise quiescent galaxies. XMM follow-up observations have proven vital to monitor their lightcurve and spectral evolution and probe their nature. These follow-up campaigns highlighted a diverse origin of the events, ranging from sources showing the characteristics of canonical Tidal Disruption Events (TDEs) to others exhibiting significant re-brightening episodes requiring alternative interpretations (e.g., partial TDEs). Here, we ask for XMM ToO observations of 8 new nuclear transients deteced by eROSITA. We will probe the diversity of the spectral and temporal evolution, enabling an improved understanding of the X-ray evolution of TDEs, and their imposters.

Details on Observing Strategy and Trigger Criteria
Trigger criteria: based on eROSITA discoveries of a new transient with :black body temperature <0.3 keV, no previous X-ray detection (including archival.), X-ray brightening by at least a factor of 10 relative to a previous upper flux detection limit. Furthermore, the host galaxy must be quiescent, i.e. not known to be an AGN. Reaction time: 1st epoch within w few weeks, 2nd epoch after 1/2 year Observing strategy: Here, we ask for ToO observations with EPIC of 8 targets, each with two visits of 20ks. The first observation of each event will be triggered within 4 weeks after the eROSITA discovery, while the second epoch will be requested to be performed approximately half a year later.