School of Physics CRA Seminar Series: Dr. Manodeep Sinha, Vanderbilt University

The large-scale distribution of galaxies can be explained fairly simply by assuming i) all galaxies are hosted by halos and ii) a cosmological model. This simple framework, called the `halo-model', has been remarkably successful at reproducing the large-scale clustering of galaxies observed in various galaxy redshift surveys. However, none of these studies have truly tested the `halo-model' by carefully modeling the systematics. We present the results from a fully-numerical, accurate `halo-model' framework and show that the theory can not simultaneously reproduce the galaxy projected correlation function and the group multiplicity function in the SDSS main samples. In particular, the bright galaxy sample shows significant tension with theory. We discuss the implications of our findings, as well as how to constrain different aspects of galaxy formation by simultaneously fitting multiple statistics.