Intergalactic Gas in Groups of Galaxies: Implications for Dwarf Spheroidal Formation and The Missing Baryons Problem

TL;DR

This study uses bent-double radio sources to directly measure the density of intergalactic gas in galaxy groups, providing insights into the missing baryons and the formation of dwarf spheroidal galaxies.

Contribution

It introduces a novel method to measure intragroup medium gas densities at large radii, supporting the hypothesis that missing baryons reside in galaxy group IGM.

Findings

Detected gas densities of 10^(-3)-10^(-4) cm^(-3) in galaxy groups.

Estimated total baryonic mass in IGM aligns with missing baryons.

IGM gas can strip gas from dwarf galaxies, influencing their evolution.

Abstract

Radio galaxies with bent jets are predominantly located in groups and clusters of galaxies. We use bent-double radio sources, under the assumption that their jets are bent by ram-pressure, to probe intragroup medium (IGM) gas densities in galaxy groups. This method provides a direct measurement of the intergalactic gas density and allows us to probe IGM gas at large radii and in systems whose IGM is too cool to be detected by the current generation of X-ray telescopes. We find gas with densities of 10^(-3)-10^(-4) per cubic centimeter at group radii from 15-700 kpc. A rough estimate of the total baryonic mass in intergalactic gas is consistent with the missing baryons being located in the IGM of galaxy groups. The neutral gas will be easily stripped from dwarf galaxies with total masses of 10^6-10^7 solar masses in the groups studied here. Indications are that IGM gas densities in less-massive systems like the Local Group should be high enough to strip gas from dwarfs like Leo T and, in combination with tides, produce dwarf spheroidals.