  Powerful winds driven by active galactic nuclei (AGN) are often invoked to
play a fundamental role in the evolution of both supermassive black holes
(SMBHs) and their host galaxies, quenching star formation and explaining the
tight SMBH-galaxy relations. Recent observations of large-scale molecular
outflows in ultra-luminous infrared galaxies (ULIRGs) have provided the
evidence to support these studies, as they directly trace the gas out of which
stars form. Theoretical models suggest an origin of these outflows as
energy-conserving flows driven by fast AGN accretion disk winds. Previous
claims of a connection between large-scale molecular outflows and AGN activity
in ULIRGs were incomplete because they were lacking the detection of the
putative inner wind. Conversely, studies of powerful AGN accretion disk winds
to date have focused only on X-ray observations of local Seyferts and a few
higher redshift quasars. Here we show the clear detection of a powerful AGN
accretion disk wind with a mildly relativistic velocity of 0.25c in the X-ray
spectrum of IRAS F11119+3257, a nearby (z = 0.189) optically classified type 1
ULIRG hosting a powerful molecular outflow. The AGN is responsible for ~80% of
the emission, with a quasar-like luminosity of L_AGN = 1.5x10^46 erg/s. The
energetics of these winds are consistent with the energy-conserving mechanism,
which is the basis of the quasar mode feedback in AGN lacking powerful radio
jets.
