0520048

Observations of the X-ray background strongly suggest that there should be a large number of highly obscured AGN inthe local Universe. However the exact number and space density of these objects remains unconstrained. These AGNare detectable by INTEGRAL. We propose to extend our observations in the XMM-LSS field and thus obtain the deepestINTEGRAL observations of an extragalactic field performed in this energy range so far which will provide a completeview of the highly obscured AGN population in the local Universe. The proposed 2 Msec observations of the XMM-LSSfield will double the expected exposure time on the field to 4 Msec thus allowing us to find ~15 extragalactic sources.These observations will significantly increase the number of AGN found in a sample selected at 20--40 keV bysampling this population to fainter fluxes. This will increase the resolved fraction of the background at these highenergies and additionally will allow us to perform more detailed spectral fitting on the brightest sources such asinvestigating the presence of a high-energy cut-off in the AGN spectra in the brightest sources as well as in the stackedspectrum of all detected AGN. These data will stand as a legacy of INTEGRAL as the deepest extragalactic softgamma-ray survey of the sky for at least the next decade. [truncated! Please see actual data for full text]