Molecular gas in Hickson compact groups

Abstract

Hickson Compact Groups of galaxies (HCG's), due to their high galaxy densities and low density environments are unique laboratories for studying galaxy interaction and evolution and determining whether the physical trends of galaxies must be explained in terms of their nature or nurture. We have observed the CO 1-0 and 2-1 emission of a sample of 51 galaxies with IRAM 30-m telescope in order to make a complete study together with previous CO observations to complete a 22 HCG's sample and make a multiwavelength (Lb, Far infrared, atomic gas) analysis. Hickson Compact Groups of galaxies (HCG's), due to their high galaxy densities and low density environments are unique laboratories for studying galaxy interaction and evolution and determining whether the physical trends of galaxies must be explained in terms of their nature or nurture. Previous observations found both their star formation rate (SFR, traced by their FIR luminosity) and H2 mass content to be lower than predicted, suggesting that the the low star formation might be due to a low gas content. We performed new CO(1-0) and CO(2-1) observations with the IRAM 30-m radiotelescope in order to test this hypothesis with a statistically significant sample. Our results agree with the previous model, showing a good correlation between the deficiency of star formation and of the gas (both atomic and molecular) content.