Galaxies and Halos in the Sloan Digital Sky Survey

Abstract

Structure formation theory provides very effective predictions of the properties of dark matter halos, including their mass function, clustering, and internal structure. Observations of structure, however, rely on luminous galaxies as tracers. A detailed understanding of the way galaxies occupy dark matter halos is essential for connecting structure formation theory to observation. We describe some of the observables available for contraining the halo occupancy, illustrating each using data from the Sloan Digital Sky Survey. Many of these observables can now be measured with great statistical precision. Comparison of these observables to theory is now limited by systematic uncertainty in the relationship between observable quantities (like velocity dispersion vs. cluster richness) and theoretically favored quantities (like M200). We argue for the use of carefully crafted simulations in making this connection, and illustrate their use in some example analyses. © 2003 American Institute of Physics