X-RAY EMISSION OF AN ULTRA-COMPACT GAMMA-RAY MILLISECOND PULSAR BINARY CANDIDATE

We propose to observe the ultracompact gammaray millisecond pulsar (MSP)candidate, 2FGL J1653.60159 jointly with NuSTAR and XMM. The Fermi source has acandidate Xray counterpart from Chandra data and its Xray and gammarayproperties are consistent with known gammaray pulsars. The source is also foundto have a 75min orbital period in optical data and possibly in a Chandraobservation. We propose to use NuSTAR and XMM to search for the orbital Xraymodulation. Moreover, the high quality energy spectra will allow us to study thespectral properties and phase resolved spectra to constrain the system geometry.A NuSTAR observation will further constrain the Xray emission mechanisms andenables a comparison with other wellknown systems. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]