Sampling ULX spectral states with XMM Newton and NuSTAR

Recently our understanding of Ultraluminous Xray Sources (ULX) has advancedsignificantly due to broad band spectrotemporal studies with XMM Newton, Suzakuand NuSTAR. Evidence now suggests that many ULXs with LX 1040ergs 1 are poweredby superEddington accretion onto black holes with masses up to 100 Mo. Thisextreme accretion regime remains poorly understood. Observations show that ULXsare variable on timescales of weeks and exhibit distinct spectral statescharacterized by multiple components in the 0.3 30 keV band. To understand thesecomponents we propose to trigger a NuSTAR and XMM Newton observation of one ofthe bright ULXs in our sample in a different spectral state than previouslyobserved. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]