The HX/FIR correlation in the local Universe

The contribution of AGNs to the Far Infrared Background is still uncertain, andis strictly related to the understanding of the energy source of ULIRGs.If a significant fraction of ULIRGs is powered by AGNs, these AGNs haveto be both luminous (L(210 keV)virgul 10^45 erg s^1) and heavily absorbed in theXrays. We propose to use the XMM observational capabilities in the hard Xrayto look for these QSO2s.. in a well defined sample of ULIRGs.We will be able to estimate a stringent lower limit of the AGN contribution toULIRGs and we expect to increase the number of known QSO2s. Comparing the Xrayand the FIR emission of these objects, we will be able to study the correlationbetween the FIR and hard Xray backgrounds in the near Universe. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]