The Mass Function of Void Galaxies in the Sloan Digital Sky Survey Data Release 2

Abstract

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 δ v < -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 that the distribution of galaxies in voids appears to be nearly unbiased compared to the mass.