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

• Published in: Astronomy and astrophysics (Berlin) Vol. 420; no. 1; pp. 79 - 88
• Main Authors: Braito, V., Della Ceca, R., Piconcelli, E., Severgnini, P., Bassani, L., Cappi, M., Franceschini, A., Iwasawa, K., Malaguti, G., Marziani, P., Palumbo, G. G. C., Persic, M., Risaliti, G., Salvati, M.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.06.2004
• Subjects: galaxies: individual: Markarian 231; X-rays: galaxies; keV range; Red shift; X-ray galaxies; Spectral properties; X-rays: galaxies; Cosmic x-ray sources; Luminosity; galaxies: individual: Markarian 231; Markarian galaxies; Absorption line; Infrared galaxies; Power law; X ray emission
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20040061

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 ($N_{\rm H}\sim 2\times 10^{24}$ 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.