Colliding Wind X-ray Emission from the Massive Binary WR140 around Periastron

The windwind collision (WWC) in eccentric massive binary systems producespredictably variable Xray plasma. This nearly controlled.. collision providesan ideal laboratory for shock astrophysics, providing key constraints on how gasthermalizes at variable density and on particle acceleration. Joint XMMNewtonand NuSTAR observation of WR 140 in AO14 discovered an extremely hard Xraycomponent, which can originate either from a kT virgul13 keV plasma or inverseCompton scattering. WR 140 will experience its periastron passage in 2016, acritical time when the WWC emission changes dramatically. We propose jointXMMNewton/NuSTAR observations of WR 140 at key phases around periastron inAO15, to determine the origin of this component and understand the Xray Minimum. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]