Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Impacts of dark energy on weighing neutrinos after Planck 2015

Xin Zhang

Abstract

We investigate how dark energy properties impact the cosmological limits on the total mass of active neutrinos. We consider two typical, simple dark energy models (that have only one more additional parameter than $Λ$CDM), i.e., the $w$CDM model and the holographic dark energy (HDE) model, as examples, to make an analysis. In the cosmological fits, we use the Planck 2015 temperature and polarization data, in combination with other low-redshift observations, including the baryon acoustic oscillations, type Ia supernovae, and Hubble constant measurement, as well as the Planck lensing measurements. We find that, once dynamical dark energy is considered, the degeneracy between $\sum m_ν$ and $H_0$ will be changed, i.e., in the $Λ$CDM model, $\sum m_ν$ is anti-correlated with $H_0$, but in the $w$CDM and HDE models, $\sum m_ν$ becomes positively correlated with $H_0$. Compared to $Λ$CDM, in the $w$CDM model the limit on $\sum m_ν$ becomes much looser, but in the HDE model the limit becomes much tighter. In the HDE model, we obtain $\sum m_ν<0.113$ eV ($95\%$ CL) with the combined data sets, which is perhaps the most stringent upper limit by far on neutrino mass. Thus, our result in the HDE model is nearly ready to diagnose the neutrino mass hierarchy with the current cosmological observations.

Impacts of dark energy on weighing neutrinos after Planck 2015

Abstract

We investigate how dark energy properties impact the cosmological limits on the total mass of active neutrinos. We consider two typical, simple dark energy models (that have only one more additional parameter than CDM), i.e., the CDM model and the holographic dark energy (HDE) model, as examples, to make an analysis. In the cosmological fits, we use the Planck 2015 temperature and polarization data, in combination with other low-redshift observations, including the baryon acoustic oscillations, type Ia supernovae, and Hubble constant measurement, as well as the Planck lensing measurements. We find that, once dynamical dark energy is considered, the degeneracy between and will be changed, i.e., in the CDM model, is anti-correlated with , but in the CDM and HDE models, becomes positively correlated with . Compared to CDM, in the CDM model the limit on becomes much looser, but in the HDE model the limit becomes much tighter. In the HDE model, we obtain eV ( CL) with the combined data sets, which is perhaps the most stringent upper limit by far on neutrino mass. Thus, our result in the HDE model is nearly ready to diagnose the neutrino mass hierarchy with the current cosmological observations.

Paper Structure

This paper contains 3 figures, 1 table.

Figures (3)

  • Figure 1: The Planck TT,TE,EE+lowP+BAO constraints on the $\Lambda$CDM (blue), $w$CDM (red), and HDE (green) models. The 68% and 95% confidence level contours are shown in the parameter planes of $\sum m_\nu$ versus $\Omega_{\rm b}h^2$, $H_0$, $\tau$, and $\sigma_8$.
  • Figure 2: The Planck TT,TE,EE+lowP+BAO+lensing+SN+$H_{0}$ constraints on the $\Lambda$CDM (blue), $w$CDM (red), and HDE (green) models. The 68% and 95% confidence level contours are shown in the parameter planes of $\sum m_\nu$ versus $\Omega_{\rm b}h^2$, $H_0$, $\tau$, and $\sigma_8$.
  • Figure 3: Two-dimensional joint, marginalized constraints (68% and 95% confidence level) on the $w$CDM and HDE models from the Planck TT,TE,EE+lowP+BAO (red) and Planck TT,TE,EE+lowP+BAO+lensing+SN+$H_{0}$ (blue) data combinations. The constraint results in the $\sum m_\nu$--$w$ (for $w$CDM, left panel) and $\sum m_\nu$--$c$ (for HDE, right panel) planes are shown.