The Unchanging Circumgalactic Medium Over the Past 11 Billion Years

TL;DR

This study finds that the circumgalactic medium's size and absorption strength around similar-mass galaxies have remained remarkably consistent over the past 11 billion years, despite evolving galaxy properties.

Contribution

It demonstrates the stability of the CGM's properties over cosmic time by comparing multiple absorption-line surveys across different redshifts.

Findings

CGM extent shows little evolution from z~2.2 to z~0.

Mean absorption equivalent width remains consistent over 11 billion years.

Results suggest a stable CGM environment despite galaxy evolution.

Abstract

This paper examines how the circumgalactic medium (CGM) evolves as a function of time by comparing results from different absorption-line surveys that have been conducted in the vicinities of galaxies at different redshifts. Despite very different star formation properties of the galaxies considered in these separate studies and different intergalactic radiation fields at redshifts between z~2.2 and z~0, I show that both the spatial extent and mean absorption equivalent width of the CGM around galaxies of comparable mass have changed little over this cosmic time interval.