Weighing neutrinos in dynamical dark energy models

We briefly review the recent results of constraining neutrino mass in dynamical dark energy models using cosmological observations and summarize the findings. (i) In dynamical dark energy models, compared to $\Lambda$CDM, the upper limit of $\sum m_\nu$ can become larger and can also become smaller. In the cases of phantom and early phantom (i.e., the quintom evolving from $w<-1$ to $w>-1$), the constraint on $\sum m_\nu$ becomes looser; but in the cases of quintessence and early quintessence (i.e., the quintom evolving from $w>-1$ to $w<-1$), the constraint on $\sum m_\nu$ becomes tighter. (ii) In the holographic dark energy (HDE) model, the tightest constraint on $\sum m_\nu$, i.e., $\sum m_\nu<0.105$ eV, is obtained, which is almost equal to the lower limit of $\sum m_\nu$ of IH case. Thus, it is of great interest to find that the future neutrino oscillation experiments would potentially offer a possible falsifying scheme for the HDE model. (iii) The mass splitting of neutrinos can influence the cosmological fits. We find that the NH case fits the current observations slightly better than the IH case, although the difference of $\chi^2$ of the two cases is still not significant enough to definitely distinguish the neutrino mass hierarchy.