Updated bounds on sum of neutrino masses in various cosmological scenarios

Abstract

We present strong bounds on the sum of three active neutrino masses ($\\sum\nm_{\\nu}$) in various cosmological models. We use the following baseline\ndatasets: CMB temperature data from Planck 2015, BAO measurements from SDSS-III\nBOSS DR12, the newly released SNe Ia dataset from Pantheon Sample, and a prior\non the optical depth to reionization from 2016 Planck Intermediate results. We\nconstrain cosmological parameters in $\\Lambda CDM$ model with 3 massive active\nneutrinos. For this $\\Lambda CDM+\\sum m_{\\nu}$ model we find a upper bound of\n$\\sum m_{\\nu} <$ 0.152 eV at 95$\\%$ C.L. Adding the high-$l$ polarization data\nfrom Planck strengthens this bound to $\\sum m_{\\nu} <$ 0.118 eV, which is very\nclose to the minimum required mass of $\\sum m_{\\nu} \\simeq$ 0.1 eV for inverted\nhierarchy. This bound is reduced to $\\sum m_{\\nu} <$ 0.110 eV when we also vary\nr, the tensor to scalar ratio ($\\Lambda CDM+r+\\sum m_{\\nu}$ model), and add an\nadditional dataset, BK14, the latest data released from the Bicep-Keck\ncollaboration. This bound is further reduced to $\\sum m_{\\nu} <$ 0.101 eV in a\ncosmology with non-phantom dynamical dark energy ($w_0 w_a CDM+\\sum m_{\\nu}$\nmodel with $w(z)\\geq -1$ for all $z$). Considering the $w_0 w_a CDM+r+\\sum\nm_{\\nu}$ model and adding the BK14 data again, the bound can be even further\nreduced to $\\sum m_{\\nu} <$ 0.093 eV. For the $w_0 w_a CDM+\\sum m_{\\nu}$ model\nwithout any constraint on $w(z)$, the bounds however relax to $\\sum m_{\\nu} <$\n0.276 eV. Adding a prior on the Hubble constant ($H_0 = 73.24\\pm 1.74$\nkm/sec/Mpc) from Hubble Space Telescope (HST), the above mentioned bounds\nfurther improve to $\\sum m_{\\nu} <$ 0.117 eV, 0.091 eV, 0.085 eV, 0.082 eV,\n0.078 eV and 0.247 eV respectively. This substantial improvement is mostly\ndriven by a more than 3$\\sigma$ tension between Planck 2015 and HST\nmeasurements of $H_0$ and should be taken cautiously. (abstract abridged)\n