Probing the impact of radio-mode feedback on the properties of the cool circumgalactic medium

TL;DR

This study investigates whether radio-mode feedback from massive galaxies affects the cool circumgalactic medium (CGM) by comparing properties around radio galaxies and non-radio galaxies, finding no significant differences but confirming substantial cool gas presence.

Contribution

It provides the first large statistical analysis of cool CGM properties around radio galaxies, constraining the impact of radio-mode feedback on the CGM.

Findings

No significant difference in MgII absorption properties between radio and non-radio galaxies.

Radio galaxies' CGM contains about 10^10 solar masses of cool gas.

Results place constraints on models of radio-mode feedback effects.

Abstract

We explore the influence of radio-mode feedback on the properties of the cool circumgalactic medium (CGM). To this end, we assemble a statistical sample of approximately 30,000 radio galaxies with background quasars by combining optical spectroscopic measurements of luminous red galaxies (LRGs) and quasars from the year 1 dataset of Dark Energy Spectroscopic Instrument (DESI) and radio sources from the LOw-Frequency ARray Two-metre Sky Survey (LoTSS) DR2 catalog and the Very Large Array Sky Survey (VLASS) quick look catalog. Galaxies with similar optical properties but with no radio counterparts in LoTSS and VLASS are selected as the control group. We measure the cool CGM properties of radio galaxies and their control samples traced by MgII absorption lines, including covering fraction, rest equivalent width, and gas kinematics. Our results show no significant difference in the properties of gas around radio galaxies and their control sample, indicating that the operating radio-mode feedback of massive galaxies does not produce detectable effects on the properties of the cool CGM. Finally, we show that the CGM of radio galaxies contain a non-negligible amount of cool gas with approximately 10^10 solar masses. This abundance can place a stringent constraint on the radio-mode feedback models.