Quasar host environments: The view from Planck

¹ DSM/Irfu/SPP, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
e-mail: loic.verdier@cea.fr; jean-baptiste.melin@cea.fr
² APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/lrfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
e-mail: bartlett@apc.univ-paris7.fr
³ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California, USA

Received: 23 September 2015
Accepted: 20 January 2016

Abstract

We measure the far-infrared emission of the general quasar (QSO) population using Planck observations of the Baryon Oscillation Spectroscopic Survey QSO sample. By applying multi-component matched multi-filters to the seven highest Planck frequencies, we extract the amplitudes of dust, synchrotron, and thermal Sunyaev-Zeldovich (SZ) signals for nearly 300 000 QSOs over the redshift range 0.1 <z< 5. We bin these individual low signal-to-noise measurements to obtain the mean emission properties of the QSO population as a function of redshift. The emission is dominated by dust at all redshifts, with a peak at z ~ 2, the same location as the peak in the general cosmic star formation rate. Restricting analysis to radio-loud QSOs, we find synchrotron emission with a monochromatic luminosity at 100 GHz (rest-frame) rising from $\overline{{\mathit{L}}_{\mathrm{synch}}}\mathrm{=}\mathrm{0}$ to 0.2 L_⊙ Hz^-1 between z = 0 and 3. The radio-quiet subsample does not show any synchrotron emission, but we detect thermal SZ between z = 2.5 and 4; no significant SZ emission is seen at lower redshifts. Depending on the supposed mass for the halos hosting the QSOs, this may or may not leave room for heating of the halo gas by feedback from the QSO.