The Mass Function of Void Galaxies in the Sdss Data Release 2

We estimate the Mass Function of void galaxies in the second public data release of the Sloan Digital Sky Survey from a sample of 1000 galaxies with local density contrasts of δv < −0.6. The galaxy sample is split into ellipticals and spirals using a color-Sérsic index criterion. We estimate the virial masses of ellipticals using the measured spectral line-widths along with the observed size. Projection effects and uncertainties in halo properties make mass estimates of spirals more difficult. We use an inversion of the Tully-Fisher relation to estimate the isothermal rotational velocity, and introduce a scaling factor to estimate the halo extent. We then fit the measured mass function against a theoretical Press-Schechter model, and find the distribution of galaxies in voids appears to be nearly unbiased compared to the mass. Subject headings: cosmology: large-scale structure of the universe – – cosmology: theory – galaxies: mass function