Observational evidence of quasar feedback quenching star formation at high redshift

TL;DR

This study provides direct observational evidence that quasar-driven outflows at high redshift can suppress star formation in their host galaxies by removing or heating the gas, supporting key galaxy evolution models.

Contribution

First direct observational proof showing quasar feedback quenches star formation in high-redshift galaxies through outflow-driven gas removal.

Findings

Detected massive outflows in a high-redshift quasar host.

Observed suppressed star formation in regions with high outflow velocity.

Confirmed quasar feedback as a mechanism for galaxy evolution at high redshift.

Abstract

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.