Constraining Agn Feedback in Massive Ellipticals With South Pole Telescope Measurements of the Thermal Sunyaev–zel’dovich Effect

Abstract

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 Sunyaev-Zeldovich (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 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   z 0.5 1.0 and one with 924 galaxies at   z 1.0 1.5, with typical stellar masses of´ M 1.5 10 . 11We then co-add the emission around these galaxies, resulting in a measured tSZ signal at s 2.2 significance for the lower redshift bin and a contaminating signal at s 1.1 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 s 3.6 for low redshifts and s 0.9 for high redshifts. We find the mean angularly integrated Compton-y values to be- 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.

Quantifying the thermal Sunyaev–Zel’dovich effect and excess millimetre emission in quasar environments

“…This has been done for massive elliptical systems (with halo mass ∼ 10 14 M ) associated with luminous red galaxies (Hand et al 2011). Others observed systems with halo mass ∼ 10 13 M that have characteristic total energies of 7 × 10 61 ergs in the circumgalactic medium (Planck Collaboration et al 2013;Greco et al 2015;Spacek et al 2016Spacek et al , 2017Spacek et al , 2018Tanimura et al 2019;Pandey et al 2019). These latter studies aim to detect fossil energy from past AGN activity -coincidentally of the same order as the cluster feedback energy scale quoted above.…”

The tau of galaxy clusters

“…Measurements of y Θ are direct observables for CMB experiments (e.g., Hand et al 2012;Planck Collaboration et al 2013b;Greco et al 2015;Spacek et al 2016). In fact, trivial modifications to certain kSZ estimators are needed to measure y Θ (e.g., Schaan et al 2016).…”

Astrophysics with the Spatially and Spectrally Resolved Sunyaev-Zeldovich Effects

“…The signal was detected with a noise level of 0.7µK at 150 GHz. These measurements, along with similar stacked measurements from ACT (Spacek et al 2017), are sensitive enough to place constraints on models of non-gravitational heating (Spacek et al 2018).…”

“…Similarly, Crichton et al (2016) stacked > 17,000 radio-quiet quasars from the SDSS in ACT data and found 3σ evidence for the presence of associated thermalised gas. The inset panel of Figure 16 illustrates the results of stacking 150 GHz data around 3394 large passive galaxies with an average stellar mass of 1.5 × 10 11 M located outside of large galaxy clusters in the data publicly released by the SPT collaboration (Spacek et al 2016). Note that at 150 GHz the SZ signal appears as a decrement, and this distinguishes it from all emission processes that can contaminate the signal.…”

“…Main figure from Scannapieco & Mauskopf in prep. Inset image from Spacek et al 2016. type galaxies. In Figure 16, we show the results of a simple estimate of the difference in the radial SZ profile around elliptical galaxies.…”