  Energetic feedback due to active galactic nuclei (AGN) is likely to play an
important role in the observed anti-hierarchical trend in the evolution of
galaxies, and yet the energy injected into the circumgalactic medium by this
process is largely unknown. One promising approach to constrain this feedback
is through measurements of CMB spectral distortions due to the thermal
Sunyaev-Zel'dovich (tSZ) effect, whose magnitude is directly proportional to
the energy input by AGN. Here we co-add South Pole Telescope SZ (SPT-SZ) survey
data around a large set of massive quiescent elliptical galaxies at z >= 0.5.
We use data from the Blanco Cosmology Survey and VISTA Hemisphere Survey to
create a large catalog of galaxies split up into two redshift bins, with 3394
galaxies at 0.5 <= z <= 1.0 and 924 galaxies at 1.0 <= z <= 1.5, with typical
stellar masses of 1.5 x 10^11 M_Sun. We then co-add the emission around these
galaxies, resulting in a measured tSZ signal at 2.2 sigma significance for the
lower redshift bin and a contaminating signal at 1.1 sigma for the higher
redshift bin. To remove contamination due to dust emission, we use SPT-SZ
source counts to model a contaminant source population in both the SPT-SZ bands
and Planck high-frequency bands for a subset of 937 low-redshift galaxies and
240 high-redshift galaxies. This increases our detection to 3.6 sigma for low
redshifts and 0.9 sigma for high redshifts. We find the mean
angularly-integrated Compton-y values to be 2.2 (-0.7+0.9) x 10^-7 Mpc^2 for
low redshifts and 1.7 (-1.8+2.2) x 10^-7 Mpc^2 for high redshifts,
corresponding to total thermal energies of 7.6 (-2.3+3.0) x 10^60 ergs and 6.0
(-6.3+7.7) x 10^60 ergs, respectively. These numbers are higher than expected
from simple theoretical models that do not include AGN feedback, and serve as
constraints that can be applied to current simulations of massive galaxy
formation. (abridged)
