Alexander Spacek, Evan Scannapieco, Seth Cohen, Bhavin Joshi, Philip Mauskopf

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Energetic feedback due to active galactic nuclei (AGNs) is likely to play an important role in the observed antihierarchical 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 SunyaevZeldovich (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 (SPTSZ) survey data around a large set of massive quiescent elliptical galaxies at z ≥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≤z≤1.0 and one with 924 galaxies at 1.0≤z≤1.5, with typical stellar masses of 1.5x 1011 M ⊙ We then co-add the emission around these galaxies, resulting in a measured tSZ signal at 2.2σ significance for the lower redshift bin and a contaminating signal at 1.1σ 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 highfrequency 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 3.6σ for low redshifts and 0.9σ for high redshifts. We find the mean angularly integrated Compton-y values to be 2.20.7 0.9x10-7Mpc2 for low redshifts and 1.7-1.8+2.210-7Mpc2 for high redshifts, corresponding to total thermal energies of 7.6-2.3 +3.0x1060 erg and 6.0-6.3 +7.71060 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.

Original languageEnglish (US)
Article number128
JournalAstrophysical Journal
Issue number2
StatePublished - Mar 10 2016


  • cosmic background radiation
  • galaxies: evolution
  • intergalactic medium
  • large-scale structure of universe
  • quasars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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