Energetic feedback due to active galactic nuclei ( AGNs ) 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 spectral distortions in the cosmic microwave background due to the thermal Sunyaev-ZelÕdovich ( tSZ ) effect , whose magnitude is directly proportional to the energy input by AGNs .
With current instruments , making such measurements requires stacking large numbers of objects to increase signal-to-noise .
While one possible target for such stacks is AGNs themselves , these are relatively scarce sources that contain contaminating emission that complicates tSZ measurements .
Here we adopt an alternative approach and co-add South Pole Telescope SZ ( SPT-SZ ) survey data around a large set of massive quiescent elliptical galaxies at z \geq 0.5 , which are much more numerous and less contaminated than active AGNs , yet are subject to the same feedback processes from the AGNs they hosted in the past .
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 : one with 3394 galaxies at 0.5 \leq z \leq 1.0 and one with 924 galaxies at 1.0 \leq z \leq 1.5 , with typical stellar masses of 1.5 \times 10 ^ { 11 } M _ { \odot } . 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 galaxies in the low-redshift bin and 240 galaxies in the high-redshift bin .
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 } \times 10 ^ { -7 } Mpc ^ { 2 } for low redshifts and 1.7 _ { -1.8 } ^ { +2.2 } \times 10 ^ { -7 } Mpc ^ { 2 } for high redshifts , corresponding to total thermal energies of 7.6 _ { -2.3 } ^ { +3.0 } \times 10 ^ { 60 } erg and 6.0 _ { -6.3 } ^ { +7.7 } \times 10 ^ { 60 } erg , 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 .