Molecular gas in galaxies at all redshifts

TL;DR

This review summarizes recent advances in understanding the molecular gas content of galaxies across all redshifts, highlighting new insights into cloud physics, star formation laws, and galaxy evolution.

Contribution

It synthesizes recent observational results from CO lines, dense tracers, and dust emission, providing a comprehensive overview of molecular gas studies in galaxies at various epochs.

Findings

Higher gas fractions in massive galaxies at earlier times

Increased turbulence and instability in galaxy disks at high redshift

Progress in interpreting star formation efficiency as a function of gas content

Abstract

I review some recent results about the molecular content of galaxies, obtained essentially from the CO lines, but also dense tracers, or the dust continuum emission. New results have been obtained on molecular cloud physics, and their efficiency to form stars, shedding light on the Kennicutt-Schmidt law as a function of surface density and galaxy type. Large progress has been made on galaxy at moderate and high redshifts, allowing to interprete the star formation history and star formation efficiency as a function of gas content, or galaxy evolution. In massive galaxies, the gas fraction was higher in the past, and galaxy disks were more unstable and more turbulent. ALMA observations will allow the study of more normal galaxies at high z with higher spatial resolution and sensitivity.