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Free keywords:
galaxies: evolution
galaxies: interactions
galaxies: star
formation
galaxies: structure
galaxies: groups: general
Astrophysics
- Astrophysics of Galaxies
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 ̃eq 10^{14} M_☉) from the Galaxy And Mass Assembly Survey, we find signatures of environmental quenching in high-mass groups (M_{ G} > 10^{12.5} M_{☉}). 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 ∆ 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_{*} ̃ 10^{10} M_{☉} 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_{☉}, 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.
