Upper Bound of 0.28 eV on the Neutrino Masses from the Largest Photometric Redshift Survey

TL;DR

This paper establishes a new, tight upper limit of 0.28 eV on the sum of neutrino masses using a large photometric redshift galaxy survey combined with multiple cosmological data sets, impacting future neutrino experiments.

Contribution

It provides the first combined neutrino mass constraint from a photometric redshift survey with other cosmological probes, tightening bounds significantly.

Findings

Upper bound of 0.28 eV on neutrino masses from combined data

Photometric redshift survey extends constraints to large scales

Results suggest upcoming neutrino experiments are unlikely to detect neutrino mass

Abstract

We present a new upper limit of sum m_{\nu} eV < 0.28 (95% CL) on the sum of the neutrino masses assuming a flat LCDM cosmology. This relaxes slightly to sum m_{\nu} < 0.34 and sum m_{\nu} < 0.47 when quasi non-linear scales are removed and w is not equal to -1, respectively. These bounds are derived from a new photometric redshift catalogue of over 700,000 Luminous Red Galaxies (MegaZ DR7) with a volume of 3.3 (Gpc h^-1)^3, extending over the redshift range 0.45 < z < 0.65 and up to angular scales of l_max = 300. The data are combined with WMAP 5-year CMB fluctuations, Baryon Acoustic Oscillations (BAO), type 1a Supernovae (SNe) and an HST prior on the Hubble parameter. This is the first combined constraint from a photometric redshift catalogue with other cosmological probes. When combined with WMAP this data set proves to be as constraining as the addition of all SNe and BAO data available to date. The upper limit is one of the tightest and `cleanest' constraints on the neutrino mass from cosmology or particle physics. Furthermore, if the aforementioned bounds hold, they all predict that current-to-next generation neutrino experiments, such as KATRIN, are unlikely to obtain a detection.