A Halo Occupation Distribution Model for redMaGiC Selected Galaxies

Andres Salcedo, Ohio State University

The observed distribution of galaxies traces the underlying cosmic large-scale structure. This structure evolved gravitationally from initial fluctuations in the primordial matter-density field. As a result, large-scale structure is particularly sensitive to the cosmological properties of the primordial matter-density field. This sensitivity can be used to constrain cosmology through a combination of data from galaxy redshift surveys, such as the Dark Energy Survey (DES), and dark-matter-only N-body simulations. This approach relies critically on accurately modeling the relationship between observed light, i.e. galaxies, and the underlying matter. One such method of modeling this relationship is through halo occupation distribution (HOD) models. HOD models specify the statistical relationship between galaxies and the dark matter halos they reside in. We present HOD fits to a redMaGiC selected galaxy population spanning a redshift range of 0.1 < z < 0.7 from year one of DES. To produce our fits, we run a Monte Carlo Markov chain using a likelihood function calibrated from measurements of the projected correlation function on mock galaxy catalogs. These mock galaxy catalogs were produced using lightcone halo catalogs generated from the Outer Rim Simulation run on the Mira supercomputer at Argonne National Laboratory.

Abstract Author(s): Andres N. Salcedo, Lindsey Bleem, Salman Habib, Katrin Heitmann, Juliana Kwan, Samuel Flender