Properties of gas phases around cosmic filaments at z=0 in the Illustris-TNG simulation

TL;DR

This study uses the Illustris-TNG simulation to analyze the properties of gas around cosmic filaments at redshift zero, revealing the dominance of warm-hot intergalactic medium and providing temperature, pressure, and SZ signal estimates.

Contribution

First detailed analysis of gas phases around cosmic filaments at z=0 using the Illustris-TNG simulation, including temperature, pressure, and observational signal predictions.

Findings

Filaments are dominated by warm-hot intergalactic medium (over 80% of baryons).

Gas in filaments is roughly isothermal up to 1.5 Mpc with temperatures of 4-13 x 10^5 K.

Predicted Sunyaev-Zel'dovich signal from filament cores ranges between 0.5 and 4.1 x 10^-8.

Abstract

We present the study of gas phases around cosmic-web filaments detected in the TNG300-1 hydro-dynamical simulation at redshift z=0. We separate the gas in five different phases according to temperature and density. We show that filaments are essentially dominated by gas in the warm-hot intergalactic medium (WHIM), which accounts for more than 80% of the baryon budget at $r \sim 1$ Mpc. Apart from WHIM gas, cores of filaments ($r<1$ Mpc) also host large contributions other hotter and denser gas phases, whose fractions depend on the filament population. By building temperature and pressure profiles, we find that gas in filaments is isothermal up to $r \sim 1.5$ Mpc, with average temperatures of T_core = $4-13 \times 10^5$ K, depending on the large scale environment. Pressure at cores of filaments is on average P_core = $4-12 \times 10^{-7}$ keV/cm^3, which is ~1000 times lower than pressure measured in observed clusters. We also estimate that the observed Sunyaev-Zel'dovich (SZ) signal from cores of filaments should range between $0.5 < y < 4.1 \times 10^{-8}$, and these results are compared with recent observations. Our findings show that the state of the gas in filaments depend on the presence of haloes, and on the large scale environment.