Exploring neutrino mass and mass hierarchy in the scenario of vacuum energy interacting with cold dark matter

Rui-Yun Guo, Jing-Fei Zhang, Xin Zhang

Published 2018-03-19Version 1

We investigate the constraints on the total neutrino mass in the scenario of vacuum energy interacting with cold dark matter. We focus on two typical interaction forms, i.e., $Q=\beta H\rho_{\rm c}$ and $Q=\beta H\rho_{\Lambda}$. To avoid the occurrence of large-scale instability in interacting dark energy cosmology, we adopt the parameterized post-Friedmann approach to calculate the perturbation evolution of dark energy. We employ the observational data including the Planck cosmic microwave background temperature and polarization data, the baryon acoustic oscillation data, the JLA sample of type Ia supernovae observation, the direct measurement of the Hubble constant, and the redshift space distortions data. We find that, compared with those in the $\Lambda$CDM model, much looser constraints on $\sum m_{\nu}$ are obtained in the $Q=\beta H\rho_{\rm c}$ model, while slightly tighter constraints are obtained in the $Q=\beta H\rho_{\Lambda}$ model. After considering the mass hierarchies of neutrinos, the smallest upper limit results of $\sum m_{\nu}$ are given in the degenerate hierarchy case. By comparing the values of $\chi^2_{\rm min}$, we find that the normal hierarchy case is more favored than the inverted one. In particular, we find that the difference $\Delta \chi^2_{\rm min} \equiv \chi^2_{\rm IH; min}-\chi^2_{\rm NH; min}> 2$ in the $Q=\beta H\rho_{\rm c}$ model. In addition, we find that $\beta=0$ is consistent with the current observations in the $Q=\beta H\rho_{\rm c}$ model, and $\beta < 0$ is favored at the more than $1\sigma$ level in the $Q=\beta H\rho_{\Lambda}$ model.