Abstract
We present strong bounds on the sum of three active neutrino masses (∑mν) using selected cosmological datasets and priors in various cosmological models. We use the following baseline datasets: Cosmic Microwave Background (CMB) temperature data from Planck 2015, Baryon Acoustic Oscillations measurements from SDSS-III BOSS DR12, the newly released Type Ia supernovae (SNe Ia) dataset from Pantheon Sample, and a prior on the optical depth to reionization from 2016 Planck Intermediate results. We constrain cosmological parameters with these datasets with a Bayesian analysis in the background of ΛCDM model with 3 massive active neutrinos. For this minimal ΛCDM + ∑mν model we find a upper bound of ∑mν < 0.152 eV at 95% C.L. Adding the high-l polarization data from Planck strengthens this bound to ∑mν < 0.118 eV, which is very close to the minimum required mass of ∑mν ≃ 0.1 eV for inverted hierarchy. This bound is reduced to ∑mν < 0.110 eV when we also vary r, the tensor to scalar ratio (Λ CDM + r + ∑mν model), and add an additional dataset, BK14, the latest data released from the Bicep-Keck collaboration (which we add only when r is varied). This bound is further reduced to ∑mν < 0.101 eV in a cosmology with non-phantom dynamical dark energy (w0waCDM + ∑mν model with w(z)⩾ −1 for all z). Considering the w0waCDM + r + ∑mν model and adding the BK14 data again, the bound can be even further reduced to ∑mν < 0.093 eV . For the w0wa CDM+∑mν model without any constraint on w(z), the bounds however relax to ∑mν < 0.276 eV . Adding a prior on the Hubble constant (H0 = 73.24±1.74 km/sec/Mpc) from Hubble Space Telescope (HST), the above mentioned bounds further improve to ∑mν < 0.117 eV, 0.091 eV, 0.085 eV, 0.082 eV, 0.078 eV and 0.247 eV respectively. This substantial improvement is mostly driven by a more than 3σ tension between Planck 2015 and HST measurements of H0 and should be taken cautiously.