xCOLD GASS: The Complete IRAM 30 m Legacy Survey of Molecular Gas for Galaxy Evolution Studies

Abstract We introduce xCOLD GASS, a legacy survey providing a census of molecular gas in the local universe. Building on the original COLD GASS survey, we present here the full sample of 532 galaxies with CO (1–0) measurements from the IRAM 30 m telescope. The sample is mass-selected in the redshift interval from the Sloan Digital Sky Survey (SDSS) and therefore representative of the local galaxy population with . The CO (1–0) flux measurements are complemented by observations of the CO (2–1) line with both the IRAM 30 m and APEX telescopes, H i observations from Arecibo, and photometry from SDSS, WISE , and GALEX . Combining the IRAM and APEX data, we find that the ratio of CO (2–1) to CO (1–0) luminosity for…