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R. R. Rojas, M. S. Vogeley, F. Hoyle (Drexel University)
Using a nearest neighbor analysis, we construct a sample of void galaxies from the Sloan Digital Sky Survey (SDSS) and compare the photometric and spectroscopic properties of these galaxies to the population of wall galaxies. We trace the density field of galaxies using a volume-limited sample extracted from the SDSS. Galaxies with fewer than three neighbors within 7h-1Mpc are classified as void galaxies. This criterion implies a density contrast \delta < -0.6 around void galaxies. From a sub-sample of 13,742 galaxies, we identify 1,010 galaxies as void galaxies. To identify an additional 194 faint SDSS void galaxies in the nearby universe, we employ volume-limited samples extracted from the Updated Zwicky Catalog and Southern Sky Redshift Survey to trace the galaxy distribution. We compare colors, concentration indices, Sersic indices, and H\alpha and OII equivalent widths of the void and wall samples. We find that void galaxies are inherently bluer and fainter than wall galaxies and that the surface brightness profiles of void galaxies more closely resemble late type galaxies. There is an excess of luminous red galaxies in the wall galaxy samples as compared to voids. Analysis of the H\alpha and OII equivalent widths confirm that void galaxies have a higher star formation rate than wall galaxies, consistent with predictions from semi-analytic models of galaxy formation.
The author(s) of this abstract have provided an email address for comments about the abstract: rrojas@newton.physics.drexel.edu
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.