Constraining Bias via Clustering in Galaxy Surveys

University Of Hawaii, Honolulu

Investigators

Abstract

AST 0206243 Szapudi Current cosmological theories imply that the stars, galaxies and clusters of galaxies that we can see represent only a relatively small fraction of the matter content of the universe. Most of the matter is in a form unknown to us, and can be detected only through its gravitational pull. The nature of this ``Dark Matter'' is the single most interesting problem in contemporary theoretical physics, and its study involves the amalgamation of information from different disciplines, such as particle physics, astronomy, and cosmology. The present project aims to constrain the properties of this elusive dark matter by looking at ``bias'', the difference between the statistical properties of visible and dark matter. According to current theories of structure formation, small initial fluctuations in the early Universe grew under the influence of gravity until the large-scale structures which, we see at the present day, formed. It appears that galaxies formed where the underlying dark matter concentrated in clumps (called halos). Thus, the present distribution of galaxies depends both on the distribution of dark matter and on the efficiency with which dark matter halos turn into galaxies. Novel statistical measures developed by Dr. Szapudi and his collaborators will be used to characterize the present-day distribution of galaxies using data from on-going wide field surveys (e.g., the Sloan Digital Sky Survey) which encompass up to a million objects. Then the theory of bias will be applied to these measured distributions to constrain the distribution of the underlying dark matter. This distribution, in turn can be used to test predictions from the various phenomenological and fundamental theories which have been developed to describe the "Dark Matter". ***