Constraints on the neutrino mass and mass hierarchy from cosmological observations

摘要

Considering the mass splitting between three active neutrinos, we represent the new constraints on the sum of neutrino mass (sum m_ u ) by updating the anisotropic analysis of the 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 ( extit{Planck})?2015 data of temperature anisotropy and polarizations of the Cosmic Microwave Background (CMB), we find that the 95?% C.L. upper bounds on (sum m_ u ) refer to (sum m_{ u ,mathrm NH}<0.18) eV for the normal hierarchy (NH), (sum m_{ u ,mathrm IH}<0.20) eV for the inverted hierarchy (IH) and (sum m_{ u ,mathrm DH}<0.15) eV for the degenerate hierarchy (DH), respectively, and the normal hierarchy is slightly preferred over the inverted one ((Delta chi ^2equiv chi ^2_mathrm{NH}-chi ^2_mathrm{IH} simeq -3.4)). In addition, the additional relativistic degrees of freedom and massive sterile neutrinos are neither favored at present.