Hard X-ray spectroscopy of two ultraluminous X-ray sources and a low-luminosity

The nature of ultraluminous Xray sources (ULXs) remains controversial. We donot know whether they host stellar or intermediatemass black holes, nor do wehave a clear understanding of the accretion process. Similarly poorly studied isthe accretion onto supermassive black holes in lowluminosity active galacticnuclei (LLAGN). To address these problems, sensitive observations at energiesabove 10 keV are needed. We propose to observe with INTEGRAL for a totalexposure of 4 Msec (2 Msec in AO7 + 2 Msec in AO8) a unique sky region where twoof the brightest ULXs, M82 X1 and Holmberg IX X1, and one of the brightestLLAGN, M81, are located. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]