Physics - Astrophysics of Galaxies Physics - Cosmology and Nongalactic Astrophysics Physics - Earth and Planetary Astrophysics Physics - High Energy Astrophysical Phenomena Physics - Instrumentation and Methods for Astrophysics Physics - Solar and Stellar Astrophysics
Astrophys.J. 624 (2005) 571-585 We study the spectroscopic properties of a sample of 10^3 void galaxies from
the Sloan Digital Sky Survey (SDSS) and compare these with the properties of
galaxies in higher density regions (wall galaxies). This sample of void
galaxies covers the range of absolute magnitude from M_r=-13.5 to M_r=-22.5 in
regions with density contrast delta < -0.6. In this paper we compare the
equivalent widths of Halpha, [OII], [NII], Hbeta, and [OIII] of void and wall
galaxies of similar luminosities and find that void galaxies have larger
values, indicating that they are still forming stars at a high rate. A
comparison of the Balmer break, as measured by the parameter Dn(4000), reveals
that void galaxies have younger stellar populations than wall galaxies. Using
standard techniques, we estimate Halpha and [OII] star formation rates of the
void and wall galaxies and along with estimates of the stellar masses, we
compute specific star formation rates. In most cases, we find that void
galaxies have similar SFRs to wall galaxies but they are fainter and smaller
mass. This means that, consistent with the EWs, void galaxies have higher
specific star formation rates than wall galaxies.