Constraints on the sum of neutrino masses using cosmological data including the latest extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample

TL;DR

This paper tightens cosmological constraints on the sum of neutrino masses $Σ m_ν$ by combining Planck 2015 CMB data with the latest eBOSS DR14 quasar BAO measurements and low-redshift observations. It analyzes the standard $νΛ$CDM model under degenerate, normal, and inverted hierarchies, finding $Σ m_ν < 0.129$ eV (DH), $<0.159$ eV (NH), and $<0.189$ eV (IH) at 95% CL, with DH moderately favored by Bayesian evidence but NH vs IH remaining indistinguishable with current data. The study also explores extended cosmologies (νwCDM, νΩ_kΛCDM, νN_effΛCDM) under the DH assumption, yielding larger $Σ m_ν$ upper limits ($<0.214$ eV, $<0.294$ eV, $<0.174$ eV respectively) and parameter constraints ($w$, $Ω_k$, $N_{ ext{eff}}$) that show modest tension with the base model according to Bayes factors. Overall, the results demonstrate that while current cosmological data constrain the neutrino mass scale, they do not decisively determine the mass hierarchy or strongly favor extended cosmologies; future high-precision measurements will be crucial for breaking remaining degeneracies.

Abstract

We investigate the constraints on the sum of neutrino masses ($Σm_ν$) using the most recent cosmological data, which combines the distance measurement from baryonic acoustic oscillation in the extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample with the power spectra of temperature and polarization anisotropies in the cosmic microwave background from the Planck 2015 data release. We also use other low-redshift observations including the baryonic acoustic oscillation at relatively low redshifts, the supernovae of type Ia and the local measurement of Hubble constant. In the standard cosmological constant $Λ$ cold dark matter plus massive neutrino model, we obtain the $95\%$ \acl{CL} upper limit to be $Σm_ν<0.129~\mathrm{eV}$ for the degenerate mass hierarchy, $Σm_ν<0.159~\mathrm{eV}$ for the normal mass hierarchy, and $Σm_ν<0.189~\mathrm{eV}$ for the inverted mass hierarchy. Based on Bayesian evidence, we find that the degenerate hierarchy is positively supported, and the current data combination can not distinguish normal and inverted hierarchies. Assuming the degenerate mass hierarchy, we extend our study to non-standard cosmological models including the generic dark energy, the spatial curvature, and the extra relativistic degrees of freedom, respectively, but find these models not favored by the data.

Figures (2)

• Figure 1: The posterior probability distribution functions of the sum of neutrino masses for three mass hierarchies of massive neutrinos. The red, green, and blue solid curves denote DH, NH, and IH, respectively. The red dashed (dot-dashed) curve denotes DH with a lower bound of $0.06\textrm{eV}$ ($0.10\textrm{eV}$) on $\Sigma m_\nu$. From left to right, the vertical dashed lines denote $\Sigma m_\nu=0.06~\mathrm{eV},~0.10~\mathrm{eV}$, respectively.
• Figure 2: Assuming the degenerate mass hierarchy, the $1\sigma$ and $2\sigma$ CL contours in the two-dimensional plane spanned by the sum of neutrino masses and the extended cosmological parameters in $\nu w$CDM, $\nu \Omega_k \Lambda$CDM, and $\nu N_{\mathrm{eff}}\Lambda$CDM, respectively. From bottom to up, the horizontal dashed lines denote $\Sigma m_\nu=0.06~\mathrm{eV},~0.10~\mathrm{eV}$, respectively.