title: Precise estimation of cosmological parameters using a more accurate likelihood function.
abstract: The estimation of cosmological parameters from a given data set requires a construction of a likelihood function which, in general, has a complicated functional form. We adopt a Gaussian copula and constructed a copula likelihood function for the convergence power spectrum from a weak lensing survey. We show that the parameter estimation based on the Gaussian likelihood erroneously introduces a systematic shift in the confidence region, in particular, for a parameter of the dark energy equation of state w. Thus, the copula likelihood should be used in future cosmological observations.
authors.affiliation: Department of Physics, Nagoya University, Nagoya 464-8602, Japan. masanori@a.phys.nagoya-u.ac.jp
authors.forename: Masanori
authors.initials: M
authors.lastname: Sato
authors.forename: Kiyotomo
authors.initials: K
authors.lastname: Ichiki
authors.forename: Tsutomu T
authors.initials: TT
authors.lastname: Takeuchi