The XMM-Newton and BeppoSAX view of the Ultra Luminous Infrared Galaxy MKN 231

We discuss XMM-Newton and BeppoSAX observations of MKN 231, the lowest-redshift Broad Absorption Line (BAL) QSO known so far and one of the best-studied Ultra Luminous Infrared Galaxies. By combining the XMM-Newton spectral resolution and the high-energy bandpass of BeppoSAX we have been able to Study in more detail than previously possible its 0.2-50 keV spectral properties. The BeppoSAX PDS data unveiled, for the first time, a highly absorbed (NHsimilar to2x10(24) cm(-2)) power-law component. We find that: a) below 10 keV we are seeing only reprocessed radiation through reflection and/or scattering; b) the intrinsic 2-10 keV luminosity of MKN 231 is 1(-0.5)(+1.0)x10(44) erg s(-1), i.e. more than an order of magnitude greater than previous measurements; c) the starburst activity significantly contributes to the soft (E<2 keV) X-ray emission.