Evidence of suppression of star formation by quasar-driven winds in
  gas-rich host galaxies at z<1?
  Feedback from active galactic nuclei (AGN) is widely considered to be the
main driver in regulating the growth of massive galaxies through heating or
driving gas out of the galaxy, preventing further increase in stellar mass.
Observational proof for this scenario has, however, been scarce. We have
assembled a sample of 132 radio-quiet type-2 and red AGN at 0.1<z<1. We measure
the kinematics of the AGN-ionized gas, the host galaxies' stellar masses and
star formation rates and investigate the relationships between AGN
luminosities, specific star formation rates (sSFR) and outflow strengths W90 --
the 90\% velocity width of the [OIII]5007 line power and a proxy for the
AGN-driven outflow speed. Outflow strength is independent of sSFR for AGN
selected on their mid-IR luminosity, in agreement with previous work
demonstrating that star formation is not sufficient to produce the observed
ionized gas outflows which have to be powered by AGN activity. More
importantly, we find a negative correlation between W90 and sSFR in the AGN
hosts with the highest SFRs, i.e., with the highest gas content, where
presumably the coupling of the AGN-driven wind to the gas is strongest. This
implies that AGN with strong outflow signatures are hosted in galaxies that are
more `quenched' than galaxies with weaker outflow signatures. Despite the
galaxies' high SFRs, we demonstrate that the outflows are not star-formation
driven but indeed due to AGN-powering. This observation is consistent with the
AGN having a net suppression, `negative' impact, through feedback on the
galaxies' star formation history.
