Abstract for Proposal 096105
Hunting for transitional millisecond pulsars with XMM-Newton, NuSTAR and VLA
The XMM discovery of a ms pulsar swinging between an accretion-powered
(X-ray) and a rotation-powered (radio) pulsar state demonstrated that
transitions between the two states can be observed over timescales of
a few weeks. We propose an XMM, NuSTAR and VLA ToO observation aimed at
studying the accretion state of transitional ms pulsars, detecting X-ray
accretion powered pulsations, and characterizing the X-ray variability
over three decades in energy. Candidates are restricted to black widows
and redbacks, systems that are in an evolutionary phase that makes
them good candidates to observe a transition. Enlarging the number of
transitional ms pulsars is crucial to test binary evolution theories,
and to study the disk-field interaction over a large range of mass
accretion rates.
Details on Observing Strategy and Trigger Criteria
A 60 ks XMM/NuSTAR observation will be triggered by a transient with
flux > 0.1 mCrab (5E-12 erg/cm2/s; 0.5-10 keV) and/or flux > 0.5 mCrab
(4E-12 erg/cm2/s; 20- 40 keV), whose position is compatible with one of
the target listed, or with an unidentified Fermi/LAT gamma-ray source
of the Galactic disk (target #47). Reaction in < 5 days will ensure the
best scientific return. Triggers of bright events such as outbursts
will be provided by X-ray transients monitoring programs performed
by ISGRI/INTEGRAL, BAT/Swift and GSC/MAXI. VLA observations must be
performed strictly simultaneous with X-ray observations for sources with
declination > -30?. For sources with declination < -30? the VLA radio
observations cannot be performed. Already accepted monitoring programs
in optical and radio bands (Galileo at La Palma, OAdM at Montsec, REM
at La Silla, PI: Papitto; FAST and GBT, PI: Parent) will be also used
to detect a transition to a fainter accretion state.