Abstract for Proposal 092104
Understanding the nature of Fast X-ray Transients
Fast X-ray Transients (FXRTs) are enigmatic extragalactic X-ray flares
of unknown origin. Thirty-three have been detected to date in archival
searches. However, none have X-ray information beyond the initial
detection. Furthermore, no simultaneous electromagnetic counterpart
to the X-ray flare has ever been detected. Three promising mechanisms
have been proposed for their origin (tidal disruptions, supernova shock
breakouts, neutron star mergers), and distinctive differences exist for
their associated X-ray spectra and luminosities. The new Einstein-Probe
mission will revolutionise this field by discovering high-flux FXRTs and
rapidly notify the community. We here propose to obtain XMM observations
of 3 FXRTs to obtain accurate spectra, light curves, and redshifts,
thereby determining their nature.
Details on Observing Strategy and Trigger Criteria
Einstein-Probe discovered FXRT with flux (0.5-4 keV)>5E-10 cgs, where
optical and NIR archival imaging show it cannot be due to a dwarf flare
star. 3 triggers of each 50 ksec requested. One observation as soon as
possible after the trigger.