# Quantifying the Thermal Sunyaev-Zel'dovich Effect and Excess Millimeter Emission in Quasar Environments

## TL;DR

This study measures the thermal Sunyaev-Zel'dovich effect in quasar environments to understand quasar-driven winds and their impact on the intergalactic medium, revealing significant energy coupling and excess emissions.

## Contribution

It provides the first measurement of the tSZ effect in a large quasar sample, linking it to quasar feedback and wind-driven hot bubbles in the intergalactic medium.

## Key findings

- Detected tSZ effect at >3.8σ significance at z>1.91.
- Estimated quasar host halo masses of ~6×10^12 h^−1 M⊙ or excess thermal energy.
- Identified excess millimeter emission at z≤1.91 likely due to CO lines or optically thick synchrotron.

## Abstract

In this paper we probe the hot, post-shock gas component of quasar-driven winds through the thermal Sunyaev-Zel'dovich (tSZ) effect. Combining datasets from the Atacama Cosmology Telescope, the $\textit{Herschel}$ Space Observatory, and the Very Large Array, we measure average spectral energy distributions (SEDs) of 109,829 optically-selected, radio quiet quasars from 1.4~GHz to 3000~GHz in six redshift bins between $0.3<z<3.5$. We model the emission components in the radio and far-infrared, plus a spectral distortion from the tSZ effect. At $z>1.91$, we measure the tSZ effect at $3.8\sigma$ significance with an amplitude corresponding to a total thermal energy of $3.1\times10^{60}$ ergs. If this energy is due to virialized gas, then our measurement implies quasar host halo masses are $\sim6\times10^{12}~h^{-1}$M$_\odot$. Alternatively, if the host dark matter halo masses are $\sim2\times10^{12}~h^{-1}$M$_\odot$ as some measurements suggest, then we measure a $>$90 per cent excess in the thermal energy over that expected due to virialization. If the measured SZ effect is primarily due to hot bubbles from quasar-driven winds, we find that $(5^{+1.2}_{-1.3}$) per cent of the quasar bolometric luminosity couples to the intergalactic medium over a fiducial quasar lifetime of 100 Myr. An additional source of tSZ may be correlated structure, and further work is required to separate the contributions. At $z\leq1.91$, we detect emission at 95 and 148~GHz that is in excess of thermal dust and optically thin synchrotron emission. We investigate potential sources of this excess emission, finding that CO line emission and an additional optically thick synchrotron component are the most viable candidates.