Evidence for the Thermal Sunyaev-Zel'dovich Effect Associated with
  Quasar Feedback
  Using a radio-quiet subsample of the Sloan Digital Sky Survey spectroscopic
quasar catalogue, spanning redshifts 0.5-3.5, we derive the mean millimetre and
far-infrared quasar spectral energy distributions (SEDs) via a stacking
analysis of Atacama Cosmology Telescope and Herschel-Spectral and Photometric
Imaging REceiver data. We constrain the form of the far-infrared emission and
find 3$\sigma$-4$\sigma$ evidence for the thermal Sunyaev-Zel'dovich (SZ)
effect, characteristic of a hot ionized gas component with thermal energy $(6.2
\pm 1.7)\times 10^{60}$ erg. This amount of thermal energy is greater than
expected assuming only hot gas in virial equilibrium with the dark matter
haloes of $(1-5)\times 10^{12}h^{-1}$M$_\odot$ that these systems are expected
to occupy, though the highest quasar mass estimates found in the literature
could explain a large fraction of this energy. Our measurements are consistent
with quasars depositing up to $(14.5 \pm 3.3)~\tau_8^{-1}$ per cent of their
radiative energy into their circumgalactic environment if their typical period
of quasar activity is $\tau_8\times~10^8$ yr. For high quasar host masses,
$\sim10^{13}h^{-1}$M$_\odot$, this percentage will be reduced. Furthermore, the
uncertainty on this percentage is only statistical and additional systematic
uncertainties enter at the 40 per cent level. The SEDs are dust dominated in
all bands and we consider various models for dust emission. While sufficiently
complex dust models can obviate the SZ effect, the SZ interpretation remains
favoured at the 3$\sigma$-4$\sigma$ level for most models.
