Normal Parameters for an Analytic Description of the CMB Cosmological Parameter Likelihood

摘要

The normal parameters are a non--linear transformation of the cosmologicalparameters whose likelihood function is very well--approximated by a normaldistribution. This transformation serves as an extreme form of data compressionallowing for practically instantaneous calculation of the likelihood of anygiven model, as long as the model is in the parameter space originallyconsidered. The compression makes all the information about cosmologicalparameter constraints from a given set of experiments available in a useablemanner. Here we explicitly define the normal parameters that work for thecurrent CMB data, and give their mean and covariance matrix which best fit thelikelihood function calculated by the Monte Carlo Markov Chain method. Alongwith standard parameter estimation results, we propose that future CMBparameter analyses define normal parameters and quote their mean and covariancematrix.