|Institution:||University of Illinois – Urbana-Champaign|
|Keywords:||cosmology: observations ??? large-scale structure of universe: observations - groups: evolution - galaxies: formation - galaxies: interactions|
|Full text PDF:||http://hdl.handle.net/2142/72905|
We present our measurements and analysis for the systematic tests, the galaxy two-point angular correlation function, and the best halo-occupation distribution (HOD) model fit for galaxies and compact galaxy groups selected from the seventh data release of the Sloan Digital Sky Survey. The galaxy sample was selected with r-band apparent magnitudes between 17 and 21; and we update the flag criteria to select a clean galaxy catalog and detail specific tests that we perform to characterize systematic effects, including the effects of seeing, Galactic extinction, and the overall survey uniformity. We measure the correlation function for the full sample as well as for the four magnitude ranges: 17???18, 18???19, 19???20, and 20???21. We find that the systematic signals are well below the galaxy angular correlation function for angles less than approximately 5???, which limits the modeling of galaxy angular correlations on larger scales. We analyze the clustering of photometrically selected galaxy pairs by using the HOD model. Our results are successfully fit by these HOD models, and we see the separation of ???1-halo??? and ???2-halo??? clustering terms for both single galaxies and galaxy pairs. We find that the galaxy pairs generally have larger clustering amplitudes than single galaxies, and the quantities computed during the HOD fitting, e.g., effective mass, M_eff , and linear bias, b_g , are also larger for galaxy pairs. We also model the clustering dependence for the galaxy pairs on redshift, galaxy type, and luminosity.