1301.1224 (Yungui Gong et al.)

On the effect of the degeneracy between w_0 and w_a    [PDF]

Yungui Gong, Qing Gao

We analytically derived two models which reduce to the familiar Chevallier-Polarski-Linder parametrization with w_a proportional to 1+w_0. The two models have only one free parameter w_0, which helps us eliminate the degeneracy among w_a, w_0 and \Omega_{m0}, and makes the models automatically consistent with the \Lambda CDM model. With these degeneracy relations, we test their effects on the constraints of cosmological parameters. We find that: (1) The degeneracy between w_0 and w_a for the two models is consistent with that found for the original Chevallier-Polarski-Linder model; (2) The degeneracies have little effect on \Omega_{m0}; (3) The 1\sigma error of \Omega_{k0} was reduced about 25% with the degeneracy relations; (4) The 1\sigma error of w_0 was reduced about one half with the degeneracy relations.

View original: http://arxiv.org/abs/1301.1224