CO and CI at redshift 2.5

摘要

We report on the first results of an in depth study of the molecular gas properties in three high-redshift sources: IRAS FSC 10214 (z = 2.3), SMMJ14011+0252 (z = 2.5) and H1413+117 (Cloverleaf quasar, z = 2.5). Our analysis is based on observations at the IRAM interferometer and the IRAM 30m telescope of atomic carbon and multiple CO lines. Our study shows that the cold molecular gas at large lookback times is already enriched to gas phase abundances similar to those found in the local universe. We find that almost all of the molecular gas in QSOs host galaxies is in form of dense gas at moderate kinetic temperatures concentrated in a compact circum nuclear toroid around the AGN. The pure starburst galaxy SMMJ14011+0252, in contrast, contains additional large amount of molecular gas at much lower density.