Observational evidence of quasar feedback quenching star formation at
  high redshift
  Most galaxy evolutionary models require quasar feedback to regulate star
formation in their host galaxies. In particular, at high redshift, models
expect that feedback associated with quasar-driven outflows is so efficient
that the gas in the host galaxy is largely swept away or heated up, hence
suppressing star formation in massive galaxies. We observationally investigate
this phenomenon by using VLT-SINFONI integral field spectroscopy of the
luminous quasar 2QZJ002830.4-281706 at z=2.4. The spectra sample the optical
emission lines redshifted into the near-IR. The [OIII]5007 emission-line
kinematics map reveals a massive outflow on scales of several kpc. The
detection of narrow Halpha emission reveals star formation in the quasar host
galaxy, with SFR=100 Msun/yr. However, the star formation is not distributed
uniformly, but is strongly suppressed in the region with the highest outflow
velocity and highest velocity dispersion. This result indicates that star
formation in this region is strongly quenched by the quasar outflow, which is
cleaning the galaxy disk of its molecular gas. This is one of the first direct
observational proofs of quasar feedback quenching the star formation at high
redshift.
