Probing Hot Gas Components of Circumgalactic Medium in Cosmological Simulations with the Thermal Sunyaev-Zel'dovich Effect

TL;DR

This study uses cosmological simulations and tSZ observations to analyze the hot gas in the circumgalactic medium, revealing feedback effects and dependencies on physical models across different halo masses.

Contribution

It provides a comprehensive comparison of tSZ signals and CGM properties across multiple simulations and observations, highlighting feedback impacts and model dependencies.

Findings

Feedback significantly affects the CGM at R₅₀₀ but diminishes beyond 5R₅₀₀.

Thermodynamic profiles vary notably with different feedback models.

Simulations align with observations, constraining feedback processes.

Abstract

The thermal Sunyaev-Zel'dovich (tSZ) effect is a powerful tool with the potential for constraining directly the properties of the hot gas that dominates dark matter halos because it measures pressure and thus thermal energy density. Studying this hot component of the circumgalactic medium (CGM) is important because it is strongly impacted by star-formation and active galactic nuclei (AGN) activity in galaxies, participating in the feedback loop that regulates star and black hole mass growth in galaxies. We study the tSZ effect across a wide halo mass range using three cosmological hydrodynamical simulations: Illustris-TNG, EAGLE, and FIRE-2. Specifically, we present the scaling relation between tSZ signal and halo mass and radial profiles of gas density, temperature, and pressure for all three simulations. The analysis includes comparisons to Planck tSZ observations and to the thermal pressure profile inferred from the Atacama Cosmology Telescope (ACT) measurements. We compare these tSZ data to the simulations to interpret the measurements in terms of feedback and accretion processes in the CGM. We also identify as-yet unobserved potential signatures of these processes that may be visible in future measurements, which will have the capability of measuring tSZ signals to even lower masses. We also perform internal comparisons between runs with different physical assumptions. We conclude: (1) there is strong evidence for the impact of feedback at $R_{500}$ but that this impact decreases by $5R_{500}$, and (2) the thermodynamic profiles of the CGM are highly dependent on the implemented model, such as cosmic-ray or AGN feedback prescriptions.