Measuring AGN Feedback with the Sunyaev-Zel'dovich Effect

TL;DR

This paper investigates how active galactic nuclei (AGN) outflows influence cosmic microwave background distortions via the Sunyaev-Zel'dovich effect, revealing measurable signatures that can inform models of galaxy evolution.

Contribution

It demonstrates that AGN feedback significantly impacts the thermal SZ effect, and proposes stacking microwave data around galaxies to detect these effects with upcoming telescopes.

Findings

AGN outflows double the angular power spectrum on arcminute scales.

Thermal SZ distortions are substantially increased around elliptical galaxies and quasars.

Stacking microwave measurements can detect AGN feedback effects in current and future observations.

Abstract

One of the most important and poorly-understood issues in structure formation is the role of outflows driven by active galactic nuclei (AGN). Using large-scale cosmological simulations, we compute the impact of such outflows on the small-scale distribution of the cosmic microwave background (CMB). Like gravitationally-heated structures, AGN outflows induce CMB distortions both through thermal motions and peculiar velocities, by processes known as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, respectively. For AGN outflows the thermal SZ effect is dominant, doubling the angular power spectrum on arcminute scales. But the most distinct imprint of AGN feedback is a substantial increase in the thermal SZ distortions around elliptical galaxies, post-starburst ellipticals, and quasars, which is linearly proportional to the outflow energy. While point source subtraction is difficult for quasars, we show that by appropriately stacking microwave measurements around early-type galaxies, the new generation of small-scale microwave telescopes will be able to directly measure AGN feedback at the level important for current theoretical models.