The first broadband study of a BH transient in quiescence with XMM and NuSTAR

Some of the most significant questions concerning the physics of black hole transients are addressed by studying BH binaries at low mass accretion rates. This is where radio observations indicate the presence of steady and powerful jets, and quiescence is where significant accretion energy may be advected across the BH event horizon. The recently launched NuSTAR mission will provide the first opportunity to probe this luminosity regime at >10 keV by observing the brightest quiescent system, V404 Cyg. We plan for coordinated radio coverage, and including XMM in this campaign is essential for: 1. constraining the shape of the broadband spectrum and the origin of the X-ray emission; 2. covering gaps in the light curve for the radio/X-ray study; and 3. for comparison to previous X-ray observations.