Feedback-driven anisotropy in the circumgalactic medium for quenching galaxies in the SIMBA simulations

TL;DR

This study uses the SIMBA simulations to analyze how bipolar AGN jet feedback creates anisotropic gas properties in the circumgalactic medium, influencing galaxy quenching and providing observable signatures.

Contribution

It demonstrates the impact of AGN jet feedback on circumgalactic gas anisotropy and its role in galaxy quenching, highlighting effects across different mass ranges and scales.

Findings

Jets cause lower densities and higher temperatures along the minor axis.

Metallicity anisotropy driven by star formation feedback extends to large scales.

AGN jets induce outflows along the minor axis, contributing to galaxy quenching.

Abstract

We use the SIMBA galaxy formation simulation suite to explore anisotropies in the properties of circumgalactic gas that result from accretion and feedback processes. We particularly focus on the impact of bipolar active galactic nuclei (AGN) jet feedback as implemented in SIMBA, which quenches galaxies and has a dramatic effect on large-scale gas properties. We show that jet feedback at low redshifts is most common in the stellar mass range $(1-5)\times 10^{10}M_\odot$, so we focus on galaxies with active jets in this mass range. In comparison to runs without jet feedback, jets cause lower densities and higher temperatures along the galaxy minor axis (SIMBA jet direction) at radii >=$0.5r_{200c}-4r_{200c}$ and beyond. This effect is less apparent at higher or lower stellar masses, and is strongest within green valley galaxies. The metallicity also shows strong anisotropy out to large scales, driven by star formation feedback. We find substantially stronger anisotropy at <=$0.5r_{200c}$, but this also exists in runs with no explicit feedback, suggesting that it is due to anisotropic accretion. Finally, we explore anisotropy in the bulk radial motion of the gas, finding that both star formation and AGN wind feedback contribute to pushing the gas outwards along the minor axis at <=1 Mpc, but AGN jet feedback further causes bulk outflow along the minor axis out to several Mpc, which drives quenching via gas starvation. These results provide observational signatures for the operation of AGN feedback in galaxy quenching.