Abstract for Proposal 087203

Hunting for transitional millisecond pulsars with XMM-Newton and NuStar

Three millisecond pulsars have recently shown to swing between an accretion (X-ray) and a rotation powered (radio) pulsar state, demonstrating that transitions between these two states can be observed over timescales as short as a few weeks. Unexpectedly, the accretion disk state of transitional millisecond pulsars is often sub-luminous in X-rays. Only a small fraction of the disk in-flow is accreted onto the NS surface, while the rest is most probably ejected by the quickly rotating magnetosphere. In this state a bright high energy emission ranging up to few GeVs is also observed.



Details on Observing Strategy and Trigger Criteria
The INTEGRAL/XMM ToO observation will be triggered as soon as the 0.3-8.0 keV flux exceeds 2E-11 erg/cm2/s (1mCrab). A reaction time of <5 days after the trigger is requested to avoid that the source fades too much for a signal search. Only one ToO observation is requested out of the 49 targets listed.