A Suzaku observation of the ULIRG IRAS19254-7245: disclosing the AGN
  component
  We discuss here a long Suzaku observation of IRAS 19254-7245 (also known as
the Superantennae), one of the brightest and well studied Ultra Luminous
Infrared Galaxies in the local Universe. This long observation provided the
first detection of IRAS 19254-7245 above 10 keV, and measured a 15-30 keV flux
of ~5x10^(-12) erg cm^-2 s^-1. The detection above 10 keV has allowed us to
unveil, for the first time, the intrinsic luminosity of the AGN hosted in IRAS
19254-7245, which is strongly absorbed (Nh ~ 3x10^(24) cm^-2) and has an
intrinsic luminosity in the QSO regime (L(2-10 keV) ~ 3 x 10^(44) erg s^-1).
The 2-10 keV spectrum of IRAS 19254-7245 is remarkably hard (Gamma~1.2), and
presents a strong iron line (EW ~0.7 keV), clearly suggesting that below 10 keV
we are seeing only reprocessed radiation. Since the energy of the Fe K emission
is found to be at ~6.7 keV, consistent with He-like Fe, and its EW is too high
to be explained in a starburst dominated scenario, we suggest that the 2--10
keV emission of IRAS 19254-7245 is dominated by reflection/scattering from
highly ionized matter. Indeed, within this latter scenario we found that the
photon index of the illuminating source is Gamma=1.87 (+0.11,-0.28), in
excellent agreement with the mean value found for radio quiet unobscured AGN.
