The Mass Function of the Stellar Component of Galaxies in the Sloan Digital Sky Survey

Abstract

Using the MOPED algorithm we determine non-parametrically the Stellar Mass Function of 96,545 galaxies from the Sloan Digital Sky Survey data release one. By using the reconstructed spectrum due to starlight we can eliminate contamination from either emission lines or AGN components. Our results give excellent agreement with previous works, but extend their range by more than two decades in mass to 10^{7.5} < M_s/h^{-2}M_\odot < 10^{12}. We present both a standard Schechter fit and a fit modified to include an extra, high-mass contribution, possibly from cluster cD galaxies. The Schechter fit parameters are $\phi^*=(7.7\pm 0.8)\times 10^{-3} h^3 Mpc^{-3}$, $M^*=(7.53 \pm 0.04) \times 10^{10} h^{-2}M_\odot$ and $\alpha=-1.167\pm 0.004$. Our sample also yields an estimate for the contribution from baryons in stars to the critical density of $\Omega_{b*}h=(2.40 \pm 0.04) \times 10^{-3}$, in good agreement with other indicators. Error bars are statistical and a Salpeter IMF is assumed throughout. We find no evolution of the mass function in the redshift range $0.05 < z < 0.34$ indicating that almost all present day stars were already formed at $z \sim 0.34$ with little or no star formation activity since then and that the evolution seen in the luminosity function must be largely due to stellar fading.