The Evolution of the Baryon Distribution in the Universe from Cosmological Simulations

TL;DR

This paper uses cosmological simulations to study how baryons are distributed across different phases over cosmic time, revealing the dominant presence of the warm-hot intergalactic medium at present and the evolution of metal enrichment.

Contribution

It provides detailed simulation-based insights into baryon phase evolution and metal enrichment mechanisms, especially the role of turbulent diffusion driven by supernovae.

Findings

Most baryons are in the warm-hot intergalactic medium at z=0.

Metal content in the WHIM increases from 4% to 22% between z=2.5 and z=0.

Simulated galaxy oxygen abundances match observed correlations.

Abstract

The evolution of the baryon distribution in different phases, derived from cosmological simulations, are here reported. These computations indicate that presently most of baryons are in a warm-hot intergalactic (WHIM) medium (about 43%) while at z = 2.5 most of baryons constitute the diffuse medium (about 74%). Stars and the cold gas in galaxies represent only 14% of the baryons at z = 0. For z < 4 about a half of the metals are locked into stars while the fraction present in the WHIM and in the diffuse medium increases with a decreasing redshift. In the redshift range 0 < z < 2.5, the amount of metals in the WHIM increases from 4% to 22% while in the diffuse medium it increases from 0.6% to 4%. This enrichment process is due essentially to a turbulent diffusion mechanism associated to mass motions driven by supernova explosions. At z = 0, simulated blue (late type) galaxies show a correlation of the oxygen abundance present in the cold gas with the luminosity of the considered galaxy that agrees quite well with data derived from HII regions.