The SAMI Galaxy Survey: observing the environmental quenching of star formation in GAMA groups

Abstract

We explore the radial distribution of star formation in galaxies in the SAMI Galaxy Survey as a function of their Local Group environment. Using a sample of galaxies in groups (with halo masses less than similar or equal to 10(14) M-circle dot) from the Galaxy And Mass Assembly Survey, we find signatures of environmental quenching in high-mass groups (M-G > 10(12.5) M-circle dot). The mean integrated specific star formation rate (sSFR) of star-forming galaxies in high-mass groups is lower than for galaxies in low-mass groups or those that are ungrouped, with Delta log(sSFR/yr(-1)) = 0.45 +/- 0.07. This difference is seen at all galaxy stellar masses. In high-mass groups, star-forming galaxies more massive than M-* similar to 10(10) M-circle dot have centrally concentrated star formation. These galaxies also lie below the star formation main sequence, which suggests they may be undergoing outside-in quenching. Lower mass galaxies in high-mass groups do not show evidence of concentrated star formation. In groups less massive than M-G = 10(12.5) M-circle dot, we do not observe these trends. In this regime, we find a modest correlation between centrally concentrated star formation and an enhancement in the total star formation rate, consistent with triggered star formation in these galaxies.