Galaxy And Mass Assembly (GAMA): Gas Fuelling of Spiral Galaxies in the Local Universe I. - The Effect of the Group Environment on Star Formation in Spiral Galaxies

M. W. Grootes, R. J. Tuffs, C. C. Popescu, P. Norberg, A. S. G. Robotham, J. Liske, E. Andrae, I. K. Baldry, M. Gunawardhana, L. S. Kelvin, B. F. Madore, M. Seibert, E. N. Taylor, M. Alpaslan, M. J. I. Brown, M. E. Cluver, S. P. Driver, J. Bland-Hawthorn, B. W. Holwerda, A. M. Hopkins, A. R. Lopez-Sanchez, J. Loveday, M. Rushton

Published 2016-12-21Version 1

Abridged - We quantify the effect of the galaxy group environment (for 12.5 < log(M_group/Msun) < 14.0) on the star formation rates of the (morphologically-selected) population of disk-dominated local Universe spiral galaxies (z < 0.13) with stellar masses log(M*/Msun) > 9.5. Within this population, we find that, while a small minority of group satellites are strongly quenched, the group centrals, and the large majority of satellites exhibit levels of SFR indistinguishable from ungrouped "field" galaxies of the same M*, albeit with a higher scatter, and for all M*. Modelling these results, we deduce that disk-dominated satellites continue to be characterized by a rapid cycling of gas into and out of their ISM at rates similar to those operating prior to infall, with the on-going fuelling likely sourced from the group intrahalo medium (IHM) on Mpc scales, rather than from the circum-galactic medium on 100kpc scales. Consequently, the color-density relation of the galaxy population as a whole would appear to be primarily due to a change in the mix of disk- and spheroid-dominated morphologies in the denser group environment compared to the field, rather than to a reduced propensity of the IHM in higher mass structures to cool and accrete onto galaxies. We also suggest that the inferred substantial accretion of IHM gas by satellite disk-dominated galaxies will lead to a progressive reduction in their specific angular momentum, thereby representing an efficient secular mechanism to transform morphology from star-forming disk-dominated types to more passive spheroid-dominated types.