Dark energy and neutrino mass constraints from weak lensing, supernova, and relative galaxy ages

TL;DR

This study combines weak lensing, supernova, baryon acoustic oscillation, and galaxy age data to constrain dark energy's equation of state and neutrino mass, finding tight bounds consistent with WMAP results.

Contribution

It demonstrates that combining multiple observational datasets significantly improves constraints on dark energy and neutrino mass, with minimal degeneracy between these parameters.

Findings

Dark energy equation of state w = -1.00^{+0.10}_{-0.12}

Neutrino mass upper limit of 0.8 eV at 95.5% confidence

Constraints are compatible with WMAP 5-year data.

Abstract

We use the current weak lensing data to constrain the equation of state of dark energy $w$ and the total mass of massive neutrinos $\sum m_{\nu}$. The constraint on $w$ would be weak if only the current weak lensing data are used. With the addition of other observational data such as the type Ia supernovae, baryon acoustic oscillation, and the high redshift Hubble parameter data $H(z)$ derived from relative galaxy ages to break the degeneracy, the result is significantly improved. For the pure $w$CDM model without massive neutrinos, we find $w=-1.00^{+0.10}_{-0.12}$. For the $w$CDM model with the massive neutrino component, we show that the constraint on $w$ is almost unchanged, there is very little degeneracy between $w$ and $\sum m_{\nu}$. After marginalizing over other parameters, we obtain the probability distribution function of $\sum m_{\nu}$, and find that the upper limit is $\sum m_{\nu} \leq 0.8$ eV at 95.5% confidence level for the combined data sets. Our constraints of $w$ and $\sum m_{\nu}$ are both compatible and comparable with the constraints obtained from the WMAP 5-year data.