Studies of galaxy evolution with redshift surveys

This thesis presents both theoretical analysis and observational results on galaxy evolution using large galaxy redshift surveys.;First, we constrained the evolution in the halo occupation distribution from z∼0:8 to z∼0:1, using two large galaxy redshift surveys: the 2-degree Field Galaxy Redshift Survey (2dF) and the DEEP2 Galaxy Redshift Survey. We found that there has been very little change in the way galaxies populate dark matter halos across half the age of the universe, which put constraints on the galaxy birth rate and merger rate.;We then applied the halo occupation model to build realistic mock catalogs for the DEEP2 Survey. Galaxies with a range of luminosities are placed within virialized dark matter halos in N-body simulations, using a variant of the halo model. The model parameters are chosen to reproduce local clustering and abundance data and assumed to be independent of redshift. This allows us to predict the luminosity function, two-point correlation function, luminosity- and scale-dependent bias, and redshift space distortion of our galaxies at higher redshifts. The catalogs have been used extensively in numerous analyses of the DEEP2 data.;I also studied how individual galaxies can evolve by targeting a special class of objects. Poststarburst galaxies exhibit spectroscopic signatures indicating that star formation was recently quenched; they are candidates for galaxies in transition from a star-forming phase to a passively evolving phase. We discovered a critical problem in the common methods for selecting these galaxies. The emission line commonly used to define poststarburst galaxies at high z, [O II] lambda3727, is heavily contaminated by LINER (Low-ionization nuclear emission region) emission in many cases. This investigation led to the discovery of a substantial AGN presence in both red, early-type galaxies and poststarburst galaxies, which shed lights on the connection between AGN activity and host galaxy evolution.;With the improved poststarburst selection method, I identified poststarburst samples in both the SDSS and DEEP2 survey datasets. Based on measurements of the overdensity of galaxies around each object, we find that poststarburst galaxies at both cosmic epochs prefer underdense environments even more strongly than star-forming galaxies. Cluster-specific formation mechanisms for poststarbursts cannot be dominant. Mergers involving gas-rich galaxies, instead, are a likely mechanism. The different environment distributions of poststarbursts and red sequence galaxies also suggest poststarburst phase is not the only evolutionary route towards the red sequence population.