# Exploring neutrino mass and mass hierarchy in interacting dark energy models

## TL;DR

This paper examines how dark energy properties influence neutrino mass constraints in interacting dark energy models using observational data, finding that dark energy dynamics affect neutrino mass bounds and hierarchy preferences.

## Contribution

It introduces a detailed analysis of neutrino mass constraints within interacting dark energy models, considering dynamical dark energy effects and their impact on neutrino hierarchy preferences.

## Key findings

- Dark energy properties influence neutrino mass constraints.
- Normal hierarchy slightly preferred over inverted hierarchy.
- Dynamical dark energy models alter upper bounds of neutrino mass.

## Abstract

We investigate how the dark energy properties impact the constraints on the total neutrino mass in interacting dark energy (IDE) models. In this study, we focus on two typical interacting dynamical dark energy models, i.e., the interacting $w$ cold dark matter (I$w$CDM) model and the interacting holographic dark energy (IHDE) model. To avoid the large-scale instability problem in IDE models, we apply the parameterized post-Friedmann approach to calculate the perturbation of dark energy. We employ the Planck 2015 cosmic microwave background temperature and polarization data, combined with low-redshift measurements on baryon acoustic oscillation distance scales, type Ia supernovae, and the Hubble constant, to constrain the cosmological parameters. We find that the dark energy properties could influence the constraint limits on the total neutrino mass. Once dynamical dark energy is considered in the IDE models, the upper bounds of $\sum m_\nu$ will be changed. By considering the values of $\chi^2_{\rm min}$, we find that in these IDE models the normal hierarchy case is slightly preferred over the inverted hierarchy case; for example, $\Delta\chi^2=2.720$ is given in the IHDE+$\sum m_\nu$ model. In addition, we also find that in the I$w$CDM+$\sum m_\nu$ model $\beta=0$ is consistent with current observational data inside the 1$\sigma$ range, and in the IHDE+$\sum m_\nu$ model $\beta>0$ is favored at more than 2$\sigma$ level.