A Comprehensive Approach to Resolving the Nature of the Dark Energy

Abstract

A data-driven approach to elucidating the nature of the dark energy, in the form of a joint analysis of a full set of cosmological parameters, utilizing all available observational data is proposed. A parameterization of a generalized dark energy is developed with the extension of fluid perturbation theory to models which cross through an equation of state of -1. This parameterization is selected to be general enough to admit a wide variety of behavior, while still being physical and economical. A Fisher matrix analysis with future high-precision CMB, cluster survey, and SNIa data suggests the parameters will probably be resolvable in the foreseeable future. How accurately the parameters can be determined depends sensitively on the nature of the dark energy - particularly how significant of a fraction of the total energy density it has been in the past. Parameter space will be sampled at a large number of points, with cosmological information such as CMB, power spectra, etc of each point being archived. Thus the likelihood functions of an arbitrary set of experiments can be applied to parameter space with insignificant new computational cost, making a wide variety of analyses possible. The resulting tool for Analysis and Resolution of Dark-sector Attributes, ARDA, will be highly versatile and adaptable. ARDA will allow the scientific community to extract parameters with an arbitrary set of experiments and theoretical priors, test for tension between classes of observations and investigate the effectiveness of hypothetical experiments, while evolving in a data-driven manner. A proof-of-concept prototype web-tool, \underbar{The Cosmic Concordance Project}, is already available.