******************************************************
   PR # 12194
    Ultraluminous infrared galaxies have the bolometric luminosities of
    QSOs but emit the bulk of their energy in the far-infrared. It has
    been proposed that these galaxies are the dust enshrouded precursors
    to normal QSOs. Hard x-rays can uniquely penetrate the dusty nuclear
    environments of these galaxies, providing a direct view of the energy
    source within. We propose to use Astro-D to measure the 2-10keV x-ray
    luminosity of four of the brightest members of the class to compare
    their x-ray-to-bolometric luminosity ratios to x-ray and optically
    selected QSOs.  We request a total of 115000 sec to observe these
    galaxies to obtain high quality spectra suitable for determining both
    the hard x-ray flux and the absorbing column towards their nuclei.

 ******************************************************