X-ray study of Ultraluminous X-ray sources with XMM-Newton and NuSTAR

We propose simultaneous observations of four Ultraluminous Xray sources withXMMNewton and the hard Xray observatory Nuclear Spectroscopic Telescope Array(NuSTAR), to be launched in February 2012. ULXs are of prime interest, as theymay be associated with a poorly explained regime of superEddington accretiononto a stellar mass black hole (BH), or even contain subEddington intermediatemass BHs. The combined observations spanning from 0.3 to more than 50 keV willremove the degeneracy of the emission model parameters derived frommulticomponent fitting of the spectra below 10keV. This broadband study willenable detailed comparisons of the ULX timing and spectral properties with thoseof better studied Galactic BH Xray binaries, delivering breakthrough information on ULX BHs. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]