A DEFINITIVE INVESTIGATION OF THE MAGNETIZED ACCRETION FLOW IN THE X-RAY PULSAR

We propose a series of four 20 ks observations with NuSTAR and XMM of theGalactic binary Xray pulsar Hercules X1, which has a 35 day superorbitalperiod caused by a warped, precessing accretion disk. The hard beam from theneutron star heats this disk and the corresponding reprocessed, thermal emissionprovides a unique opportunity for observation of magneticdominated accretion.Our proposed analysis requires good spectral and timing resolution across thefull energy band (<1 keV to >20 keV) in order to constrain both the softemission from the disk and the pulsar beam. For the first time, we will track acomplete precession of Her X1a??s accretion disk with full hard Xray coverageto gain the clearest picture to date of the structure and kinematics of the magnetized accretion flow. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]