Investigating the impact of group environment on galaxy properties

<p>The properties of galaxies, such as their shape and star formation rate (SFR), correlate strongly with the galaxy number density in the surrounding Universe. This is well known for cluster galaxies, which show a suppression of the star formation activity with respect to the field, but the situation is less clear for groups.</p> <p>The aim of this research is to explore whether and how the group environment may affect the star formation properties of infalling star-forming galaxies. We use the Galaxy And Mass Assembly (GAMA) group catalogue, finding that the specific SFR of star-forming members declines at ∼ 3.5 <em>R</em>₂₀₀ towards the group centre by a factor ∼ 1.3 with respect to field galaxies. We explore the use of the projected phase space (PPS) diagram, i.e. the galaxy velocity as a function of projected group-centric radius, as an environment metric in the group mass regime. The PPS has been extensively used for investigating more massive clusters where the position of a galaxy in the PPS correlates with time since infall. Similar to cluster studies, we find that the fraction of star-forming group galaxies is higher in the PPS regions dominated by recently accreted galaxies, whereas passive galaxies dominate the virialised regions.</p>