The circumgalactic medium of various galaxies

The circumgalactic medium (CGM) consists of gaseous halos surrounding galaxies, and its existence is both theoretically predicted and observationally confirmed. The CGM plays a crucial role in galaxy formation theory and is important for determining the accretion and star formation rates of galaxies, as well as for stellar and active galactic nucleus (AGN) feedback processes. This discussion will cover the processes that shape the CGM of low-redshift M* galaxies, intermediate-redshift (z~2) M* galaxies, and high-redshift (z>9) galaxies observed with the James Webb Space Telescope (JWST). 

At low redshifts, reproducing the observed data requires understanding the interaction between stellar winds and the hydrostatic halo, as well as the thermodynamic properties of the various gas phases present. At intermediate redshifts, galactic halos are penetrated by cold streams of gas that free-fall into the halo while undergoing Kelvin-Helmholtz shear instabilities. At high redshifts, the extreme densities of the infalling gas decrease various timescales, allowing for star formation at unprecedented efficiencies of almost 100%.