Measuring AGN Feedback with the Sunyaev-Zel’dovich Effect

One of the most important and poorly understood issues in structure formation is the role of outflows driven by active galactic nuclei (AGNs). 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 through both 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, poststarburst elliptical galaxies, and quasars that 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 that is important for current theoretical models.