089071

We propose a joint NuSTAR and XMM observation of NGC4631 openPard=7MpcclosePar comma a nearby metal-poor galaxy openParZ-Z sun virgul 0.2closePar with multiple luminous HMXBs. We will openPar1closePar examine the nature and accretion states of the HMXBs via color diagnostics comma openPar2closePar measure the galaxy-integrated 0.3-30 keV spectrum to calibrate the bolometric correction for low metallicity galaxies comma and openPar3closePar investigate the contribution of each bright source to this spectrum. As an ancillary science goal comma we will search for the signature of inverse Compton emission from electrons accelerated in the magnetic field of the galaxy.