Abstract for Proposal 092034
Search for X-ray fast transitional mode switching in an accreting white dwarf
Accreting white dwarfs were known so far to display luminosity variation
on timescales of days or longer. The recent discovery of abrupt changes
in the optical flux in the cataclysmic variable TWPic as short as 30m has
opened a new window in our knowledge of accretion processes and points
to strong similarities to the mode switching observed in transitional
millisecond pulsars. We aim at detecting for the first time the X-ray
analog of such a phenomenon so far observed only in the optical. We ask
for a XMM-Newton ToO 120 ks exposure to pin-point a long low mode in
this system primarily triggered by optical monitoring. We will study
the short-term variability during bursts occurring only during in the
low-mode and search for the spin period of the accreting white dwarf.
Details on Observing Strategy and Trigger Criteria
We will trigger the XMM-Newton observation of TW Pic when entering
in a long-lasting (>7-10days) low-mode. For the trigger we will use
ground-based optical ASAS-SN daily monitoring and when not visibile from
ground (2months in summer 2023) we will use Swift with a separate request
in case TW Pic has not entered in a long low-mode at that time. We request
a reaction time of one week in agreement with the minimal reaction time
policy. The exposure of 120ks to be performed with the EPIC-pn as primary
camera in Large Window mode with the thin filter .