The Nature of Ultra-Luminous Compact X-ray Sources

We propose to establish the nature of the ultraluminous Xray sources (Lx greater than 4e39 erg/s). These may be a new type of accretingsystem, with the compact object mass approx 100 Msun an intermediate massblack hole. This is currently controversial and alternative models of a stellarmass black hole with beamed emission are also being championed. If they areintermediate mass black holes their origin may be primordial, or the result ofgalaxy or black hole mergers. We will use high S/N spectra, timing studies andXray/UV imaging to distinguish between the two scenarios. Only XMMNewton withits large collecting area, long exposures and good PSF can obtain the timing andspectral data necessary to determine the nature of these objects. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]