Letter to the Editor

Observational evidence of quasar feedback quenching star formation at high redshift^⋆,⋆⋆

¹ INAF – Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monteporzio Catone, Italy
e-mail: maiolino@oa-roma.inaf.it
² Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Ave., Cambridge CB3 0HE, UK
³ Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Largo E. Fermi 2, 50125 Firenze, Italy
⁴ School of Physics and Astronomy and the Wise Observatory Tel-Aviv University, 69978 Tel-Aviv, Israel
⁵ Department of Physics, University of North Texas, Denton, TX 76203, USA
⁶ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

Received: 28 October 2011
Accepted: 16 December 2011

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]λ5007 emission-line kinematics map reveals a massive outflow on scales of several kpc. The detection of narrow Hα emission reveals star formation in the quasar host galaxy, with SFR ~ 100   M_⊙ yr^-1. 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.