Testing Galaxy Formation with Clustering Statistics and ΛCDM Halo Models at z=0-1

Date: Wed. September 10th, 2014, 11:00 am-1:00 pm
Location: Sears 552

Testing Galaxy Formation with Clustering Statistics and ΛCDM Halo Models at z=0-1

Ramin Skibba, UC San Diego

Galaxies form and evolve in particular environments of the cosmic web, which consists of a variety of filaments and knots, as well as voids and underdense regions. The influence of a galaxy’s environment on its evolution has been studied and compared extensively in the literature, although differing techniques are often used to define ‘environment.’ I will begin by assessing measures of environmental correlations using mock galaxy catalogs. I will introduce a new method for quantifying environmental correlations, namely, mark clustering statistics. I find that mark correlation functions are able to detect even a small dependence of galaxy properties on the environment–better than traditional methods– and I show that rank ordering the marks and using the rank as a weight is a simple way of comparing the correlation signals for different marks. Next, I will present galaxy clustering measurements from the PRIMUS survey, which quantify galaxies’ environmental dependencies over the past eight billion years of cosmic time. In this context, I will also comment on ‘cosmic variance,’ the sampling fluctuations among different regions of the Universe, which plague some other studies in the literature. I will present clustering and bias results from preliminary dark matter halo models as well as new results with more realistic models. I will argue that clustering evolution since z~1 is consistent with ‘passive evolution,’ that the stellar mass-halo mass relation and similar relations have not significantly evolved over this time, and that the efficiency of satellite galaxy formation was higher at higher redshift, which have implications for subhalo abundance matching approaches.