Constraints on the neutrino mass and mass hierarchy from cosmological observations

Qing-Guo Huang,Sai Wang,Ke Wang

doi:10.1140/epjc/s10052-016-4334-z

Abstract

Considering the mass splitting between three active neutrinos, we represent the new constraints on the sum of neutrino mass $\sum m_\nu$ by updating the anisotropic analysis of Baryon Acoustic Oscillation (BAO) scale in the CMASS and LOWZ galaxy samples from Data Release 12 of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS DR12). Combining the BAO data of 6dFGS, MGS, LOWZ and CMASS with $\textit{Planck}$~2015 data of temperature anisotropy and polarizations of Cosmic Microwave Background (CMB), we find that the $95\%$ C.L. upper bounds on $\sum m_\nu$ refer to $\sum m_{\nu,\rm NH}<0.18$ eV for normal hierarchy (NH), $\sum m_{\nu,\rm IH}<0.20$ eV for inverted hierarchy (IH) and $\sum m_{\nu,\rm DH}<0.15$ eV for degenerate hierarchy (DH) respectively, and the normal hierarchy is slightly preferred than the inverted one ($\Delta \chi^2\equiv \chi^2_{\rm NH}-\chi^2_{\rm IH} \simeq -3.4$). In addition, the additional relativistic degrees of freedom and massive sterile neutrinos are neither favored at present.

Highlights

The phenomena of neutrino oscillation imply that there are mass splittings between the three active neutrinos
Combining the Baryon Acoustic Oscillation (BAO) data of 6dFGS, MGS, LOWZ and CMASS with Planck 2015 data of temperature anisotropy and polarizations of the Cosmic Microwave Background (CMB), we find that the 95 % C.L. upper bounds on mν refer to mν,NH < 0.18 eV for the normal hierarchy (NH), mν,IH < 0.20 eV for the inverted hierarchy (IH) and mν,DH < 0.15 eV for the degenerate hierarchy (DH), respectively, and the normal hierarchy is slightly preferred over the inverted one ( χ 2 ≡ χN2H − χI2H −3.4)
We refer to two combinations of datasets, namely Planck TT, TE, EE + lowP + BAO and Planck TT + lowP + lensing + BAO, to constrain the sum of the neutrino mass mν with NH, IH, and DH, respectively

Summary

Introduction

The phenomena of neutrino oscillation imply that there are mass splittings between the three active neutrinos (see [1] for a review). Massive neutrinos are initially relativistic and become non-relativistic today They can impact on the cosmic expansion since they evolve differently from pure radiations and pure cold dark matter. By contrast, adding the Baryon Acoustic Oscillation (BAO) data including 6dFGS [22], MGS [23], BOSS DR11 CMASS [24] and LOWZ [24] can significantly improve the constraints to mν < 0.21 eV and mν < 0.17 eV, respectively. In this paper we update the constraints on the total mass of three active neutrinos by using BOSS DR12 CMASS and LOWZ data, which are combined with other cosmological observations such as Planck 2015 CMB data. 3, we demonstrate our constraints on the sum of the neutrino mass, additional relativistic degrees of freedom, and massive sterile neutrinos, respectively.

Data and method

Results

Constraints on mν

Constraints on Neff

Conclusions