We present an analysis of the properties of the lowest Halpha-luminosity galaxies (L_Halpha<4x10^32 W; SFR<0.02 Msun/yr) in the Galaxy And Mass Assembly (GAMA) survey. These galaxies make up the the rise above a Schechter function in the number density of systems seen at the faint end of the Halpha luminosity function. Above our flux limit we find that these galaxies are principally composed of intrinsically low stellar mass systems (median stellar mass =2.5x10^8 Msun) with only 5/90 having stellar masses M>10^10 Msun. The low SFR systems are found to exist predominantly in the lowest density environments (median density ~0.02 galaxy Mpc^-2 with none in environments more dense than ~1.5 galaxy Mpc^-2). Their current specific star formation rates (SSFR; -8.5 < log(SSFR[yr^-1])<-12.) are consistent with their having had a variety of star formation histories. The low density environments of these galaxies demonstrates that such low-mass, star-forming systems can only remain as low-mass and forming stars if they reside sufficiently far from other galaxies to avoid being accreted, dispersed through tidal effects or having their gas reservoirs rendered ineffective through external processes.
@article{arxiv.1012.3771,
title = {Galaxy And Mass Assembly (GAMA): Galaxies at the faint end of the Halpha luminosity function},
author = {S. Brough and A. M. Hopkins and R. G. Sharp and M. Gunawardhana and D. Wijesinghe and A. S. G. Robotham and S. P. Driver and I. K. Baldry and S. P. Bamford and J. Liske and J. Loveday and P. Norberg and J. A. Peacock and J. H. Bland-Hawthorn and M. J. I. Brown and E. Cameron and S. M. Croom and C. S. Frenk and C. Foster and D. T. Hill and D. H. Jones and L. S. Kelvin and K. Kuijken and R. C. Nichol and H. R. Parkinson and K. Pimbblet and C. C. Popescu and M. Prescott and W. J. Sutherland and E. Taylor and D. Thomas and R. J. Tuffs and E. van Kampen},
journal= {arXiv preprint arXiv:1012.3771},
year = {2015}
}