Comparison of some properties of star forming galaxies and active galactic nuclei (AGNs) between two BOSS galaxy samples of SDSS DR9

Abstract

Using the LOWZ and CMASS samples of the ninth data release (DR9) from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), I investigate properties of star forming galaxies and AGNs. The CMASS sample seriously suffers from the radial selection effect, even within the redshift 0.44<z<0.6, which will lead to statistical conclusions in the CMASS sample being less likely robust. In the LOWZ sample, the fraction of star-forming galaxies is nearly constant from the lowest density regime to the densest regime; the AGN fraction is also insensitive to the local environment. In addition, I note that in the LOWZ sample, stellar mass and stellar velocity dispersion distributions of star forming galaxies and AGNs are nearly same.