xCOLD GASS: an IRAM legacy survey

The IRAM-30m reference CO survey for galaxy evolution studies

xCOLD GASS is a reference survey for galaxy evolution studies: it provided a complete view of the molecular gas contents of galaxies in the nearby Universe. It is allowing us to investigate the interplay between cold gas and star formation, and the mechanisms that contribute to galaxy growth and quenching.

The survey is the combination of two IRAM-30m large programmes. Through almost 1000 hours of observations over the course of 6 years, the xCOLD GASS team measured emission from the CO molecule in 532 galaxies selected from the Sloan Digital Sky Survey. The xCOLD GASS sample is purely selected by mass, and therefore contains a mix of galaxies representative of the entire local galaxy population.

xCOLD GASS builds upon GALEX, SDSS and WISE imaging, but mostly upon its twin project xGASS, an Arecibo survey of atomic gas in an unbiased sample of 1200 nearby galaxies. Through its robust sample selection and homogeneous observations, xCOLD GASS provides the definitive census of the partition of condensed baryons into stars, atomic and molecular gas in galaxies with stellar masses of 109-1011.5 M in the local Universe.