Major problem with current standard model of cosmology resolved

Scientists have solved a major problem with the current standard model of cosmology by combining results from the Planck spacecraft and measurements of gravitational lensing in order to deduce the mass of ghostly sub-atomic particles called neutrinos.

The team, from the universities of Manchester and Nottingham, used observations of the Big Bang and the curvature of space-time to accurately measure the mass of these elementary particles for the first time.

The Cosmic Microwave Background (CMB) is the oldest light in the universe, and its study has allowed scientists to accurately measure cosmological parameters, such as the amount of matter in the universe and its age.

But an inconsistency arises when large-scale structures of the universe, like the distribution of galaxies, are observed.

Professor Richard Battye, from the University of Manchester's School of Physics and Astronomy, said that they observe fewer galaxy clusters than they would expect from the Planck results and there is a weaker signal from gravitational lensing of galaxies than the CMB would suggest.

Professor Battye and co-author Dr. Adam Moss, from the University of Nottingham, combined the data from Planck with gravitational lensing observations in which images of galaxies are warped by the curvature of space-time, and concluded that the current discrepancies can be resolved if massive neutrinos are included in the standard cosmological model.

They estimate that the sum of masses of neutrinos is 0.320 +/- 0.081 eV (assuming active neutrinos with three flavors).

The paper has been published in Physical Review Letters.