Missing Baryons and the Warm-Hot Intergalactic Medium

TL;DR

This paper discusses the missing baryons in the universe, which are believed to reside in the warm-hot intergalactic medium formed by shock-heated matter during cosmic structure formation, crucial for understanding cosmology.

Contribution

It highlights the importance of detecting the warm-hot intergalactic medium to account for all baryons and validate cosmological models.

Findings

Most baryons are in the warm-hot intergalactic medium

Shock-heating during structure formation explains baryon distribution

Detecting this medium is key to completing the cosmic baryon inventory

Abstract

Stars and gas in galaxies, hot intracluster medium, and intergalactic photo-ionized gas make up at most half of the baryons that are expected to be present in the universe. The majority of baryons are still missing and are expected to be hidden in a web of warm-hot intergalactic medium. This matter was shock-heated during the collapse of density perturbations that led to the formation of the relaxed structures that we see today. Finding the missing baryons and thereby producing a complete inventory of possibly the only detectable component of the energy-mass budget of the universe is crucial to validate or invalidate our standard cosmological model.