Faint CO Line Wings in Four Star-Forming (Ultra)luminous Infrared
  Galaxies
  We report the results of a search for large velocity width, low-intensity
line wings - a commonly used signature of molecular outflows - in four low
redshift (ultra)luminous infrared galaxies (U/LIRGs) that appear to be
dominated by star formation. The targets were drawn from a sample of fourteen
such galaxies presented in Chung et al. (2011), who showed the stacked CO
spectrum of the sample to exhibit 1000 km/s-wide line wings. We obtained
sensitive, wide bandwidth imaging of our targets using the IRAM Plateau de Bure
Interferometer. We detect each target at very high significance but do not find
the claimed line wings in these four targets. Instead, we constrain the flux in
the line wings to be only a few percent. Casting our results as mass outflow
rates following Cicone et al. (2014) we show them to be consistent with a
picture in which very high mass loading factors preferentially occur in systems
with high AGN contributions to their bolometric luminosity. We identify one of
our targets, IRAS05083 (VII Zw 31), as a candidate molecular outflow.
