An enshrouded active galactic nucleus in the merging starburst system ARP 299 revealed by BeppoSAX

Using a long (similar or equal to150 ks) broadband (0.1- 40 keV) BeppoSAX observation of the merging starburst system Arp 299 (=IC 694 + NGC 3690), we found the first unambiguous evidence of the presence of a deeply buried (N-H similar or equal to 2.5 x 10(24) cm(-2)) active galactic nucleus (AGN) having an intrinsic luminosity of L0.5-100 (keV) similar or equal to 1.9 x 10(43) ergs s(-1). The X- ray spectral properties of this AGN are discussed in detail, as well as the thermal component detected at soft X- ray energies, which, most likely, is associated with the starburst.