Limit on the Neutrino Mass from the WMAP Three Year Data

Abstract

We derive an upper limit on the neutrino mass from the WMAP three-year data alone by employing a deterministic minimisation method based on a grid search in multi-parameter space. Assuming the flat LCDM model with power-law adiabatic perturbations, we find the sum of m_nu < 2.0 eV in agreement with the result of the WMAP team. This result, the limit being nearly the same as that from the WMAP first-year data, means that the fundamental limit on the neutrino mass obtainable from the cosmic microwave background alone is already nearly met, as anticipated from the previous analysis. We also clarify the role of the polarisation data in deriving the limit on the neutrino mass.

Figures (2)

• Figure 1: The curve of $\chi^2(\omega_\nu)$ as a function of the neutrino mass summed over generations. The solid curve uses all available data from WMAP including polarisations. The dotted curve is a constraint from only temperature-temperature correlations.
• Figure 2: TT, TE and EE correlators for three cases: $\omega_\nu =$0 (the solid line) and 0.02 (the dashed line) with the other parameters fixed to the WMAP mean values. In the right panels the abscissa is rescaled according to the modification of the acoustic length that varies with the neutrino mass.