On the Star Formation Properties of Void Galaxies
  We measure the star formation properties of two large samples of galaxies
from the SDSS in large-scale cosmic voids on time scales of 10 Myr and 100 Myr,
using H$\alpha$ emission line strengths and GALEX FUV fluxes, respectively. The
first sample consists of 109,818 optically selected galaxies. We find that void
galaxies in this sample have higher specific star formation rates (SSFRs; star
formation rates per unit stellar mass) than similar stellar mass galaxies in
denser regions. The second sample is a subset of the optically selected sample
containing 8070 galaxies with reliable HI detections from ALFALFA. For the full
HI detected sample, SSFRs do not vary systematically with large-scale
environment. However, investigating only the HI detected dwarf galaxies reveals
a trend towards higher SSFRs in voids. Furthermore, we estimate the star
formation rate per unit HI mass (known as the star formation efficiency; SFE)
of a galaxy, as a function of environment. For the overall HI detected
population, we notice no environmental dependence. Limiting the sample to dwarf
galaxies again reveals a trend towards higher SFEs in voids. These results
suggest that void environments provide a nurturing environment for dwarf galaxy
evolution allowing for higher specific star formation rates and efficiencies.
