Galaxy And Mass Assembly (GAMA): impact of the group environment on galaxy star formation

Abstract

We explore how the group environment may affect the evolution of star-forming galaxies. We select 1197 Galaxy And Mass Assembly (GAMA) groups at $0.05\leq z \leq 0.2$ and analyze the projected phase space (PPS) diagram, i.e. the galaxy velocity as a function of projected group-centric radius, as a local environmental metric in the low-mass halo regime $10^{12}\leq (M_{200}/M_{\odot})< 10^{14}$. We study the properties of star-forming group galaxies, exploring the correlation of star formation rate (SFR) with radial distance and stellar mass. We find that the fraction of star-forming group members is higher in the PPS regions dominated by recently accreted galaxies, whereas passive galaxies dominate the virialized regions. We observe a small decline in specific SFR of star-forming galaxies towards the group center by a factor $\sim 1.2$ with respect to field galaxies. Similar to cluster studies, we conclude for low-mass halos that star-forming group galaxies represent an infalling population from the field to the halo and show suppressed star formation.