Relationship between Gas Content and Luminosities in Virgo Galaxies

Extract

Galaxies in the Virgo cluster offer a convenient distance independent sample for the study of large scale properties of star formation (SF). While the gas is the raw material for SF, the galaxy mass seems to play an important role. The luminosities in various bands are sensitive to stars of different masses (ages) and as such sample SF over different periods of time. For example, the far-infrared (far-IR) luminosity samples recent (few tens of million years) and massive stars, while the blue luminosity samples stars over about billion years. The H band luminosity represents almost the average SF over the life of the galaxy. Relationships between luminosities and gas contents, can then offer clues to the history of SF in the galaxy and its variation from galaxy to galaxy. In order to be free of richness effects, correlations are studied by normalising with M(G), the dynamic mass within the optical diameter of the galaxy. The mass normalised quantities will be referred to as specific mass and specific luminosity.