The correlation of metallicity gradient with galaxy mass

A number of previous studies have searched for a correlation between radial metallicity gradients and early-type galaxy mass - no convincing trends have been found. Here we re-examine this issue with several key enhancements: using total metallicity from studies that have broken the age-metallicity degeneracy, excluding galaxies with young stellar ages (i.e. those that have experienced a recent central starburst) and using the K band to derive galaxy luminosities. We find that Coma cluster galaxies have metallicity gradients that correlate with galaxy mass. Furthermore, gradients have values similar to those of monolithic collapse models. The combination of dissipative formation and energy injection from supernovae provides a mechanism for the trends with galaxy mass; however, other explanations are possible. Additional high-quality observational data are needed to constrain further the gas physics involved in galaxy formation.