A global fit study on the new agegraphic dark energy model

TL;DR

This study performs a comprehensive global fit analysis of the new agegraphic dark energy model using multiple cosmological datasets, revealing a preference for an open universe and providing updated parameter constraints.

Contribution

It offers the first detailed MCMC analysis of the NADE model with full CMB, SNIa, BAO, and H0 data, highlighting the impact of different SNIa samples on parameter estimation.

Findings

NADE favors an open universe with Ω_k0 > 0 at 3σ CLs

The key parameter n is constrained to approximately 2.67, smaller than previous estimates

Replacing the SNIa sample reduces tension and yields more reliable constraints

Abstract

We perform a global fit study on the new agegraphic dark energy (NADE) model in a non-flat universe by using the MCMC method with the full CMB power spectra data from the WMAP 7-yr observations, the SNIa data from Union2.1 sample, BAO data from SDSS DR7 and WiggleZ Dark Energy Survey, and the latest measurements of $H_0$ from HST. We find that the value of $\Omega_{k0}$ is greater than 0 at least at the 3$\sigma$ confidence levels (CLs), which implies that the NADE model distinctly favors an open universe. Besides, our results show that the value of the key parameter of NADE model, $n=2.673^{+0.053+0.127+0.199}_{-0.077-0.151-0.222}$, at the 1--3$\sigma$ CLs, where its best-fit value is significantly smaller than those obtained in previous works. We find that the reason leading to such a change comes from the different SNIa samples used. Our further test indicates that there is a distinct tension between the Union2 sample of SNIa and other observations, and the tension will be relieved once the Union2 sample is replaced by the Union2.1 sample. So, the new constraint result of the NADE model obtained in this work is more reasonable than before.