  The feedback from galactic outflows is thought to play an important role in
shaping the gas content, star formation history, and ultimately the stellar
mass function of galaxies. Here we present evidence for massive molecular
outflows associated with ultra-luminous infrared galaxies (ULIRGs) in the
coadded Redshift Search Receiver 12CO(1-0) spectrum. Our stacked spectrum of 27
ULIRGs at z = 0.043-0.11 (freq_rest = 110-120 GHz) shows broad wings around the
CO line with delta_V(FWZI)~2000 km/s. Its integrated line flux accounts for up
to 25+/-5% of the total CO line luminosity. When interpreted as a massive
molecular outflow wind, the associated mechanical energy can be explained by a
concentrated starburst with SFR \geq 100 M_sun/yr, which agrees well with their
SFR derived from the FIR luminosity. Using the high signal-to-noise stacked
composite spectrum, we also probe 13CO and 12CN emission in the sample and
discuss how the chemical abundance of molecular gas may vary depending on the
physical conditions of the nuclear region.
