Abstract for Proposal 094251
XMM-Newton Follow-Up of a Newly Discovered Repeating Nuclear Transient
Galactic nuclei showing recurrent phases of activity and quiescence
have recently been discovered -- with recurrence times as short as
a few hours to a day known as quasi-periodic X-ray eruption (QPE)
sources, to as long as hundreds to a thousand days for repeating nuclear
transients (RNTs). The recent discovery of Swift J0230+28, showing an
X-ray eruption every 22 days, marks an intermediate timescale between
known QPEs and longer RNTs, and reveals a continuum of timescales for
RNTs. The emergence of this population is particularly exciting given
their potential use to probe nuclear stellar dynamics in external
galaxies. Here, we propose 90ks ToO observations of a new RNT. We aim
to perform time-resolved spectroscopy, the results of which can be used
to differentiate competing models.
Details on Observing Strategy and Trigger Criteria
Triggering Criteria: We will trigger this program for any newly discovered
nuclear transient that shows repeating phases of activity and quiescence,
including the short-time-scales QPE sources and longer-time-scale
RNTs. We will also require the source to be at least as bright as a
0.3-10.0 keV flux of $\geq 5\times10^{-13}$ cgs at the peak of the high
activity phases, so that enough counts are collected for time-resolved
spectroscopy ($> 5000$ counts). We will will divide our observations in
2x45ks, and request a reaction time of 5 days for the first one and of
2 weeks for the second.