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

We discuss XMM-Newtonand 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-Newtonspectral 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 ($N_{\rm H}\sim 2\times 10^{24}$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^{+1.0}_{-0.5} \times 10^{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.