Using peculiar velocity surveys to constrain neutrino masses

Abstract

ABSTRACT The presence of massive neutrinos in the early Universe is expected to have influenced the observed distribution of galaxies and their observed motions. In this work, we explore whether measurements of galaxy peculiar velocities could allow us to improve upon neutrino mass constraints from galaxy redshift surveys alone. Using Fisher matrix forecasts, we show that the galaxy peculiar motions do contain information on the sum of the masses of neutrinos ∑mν, and that this information can be used to improve upon constraints that may be obtained from low-redshift galaxy surveys (z < 0.5) combined with Planck measurements of the cosmic microwave background. Compared to the full constraining power offered by Planck and higher redshift DESI data, we find that the benefit of including peculiar velocities only marginally improves neutrino mass constraints. However, when one does not include information from Planck, our results show that the inclusion of peculiar velocity measurements can substantially improve upon the constraints from redshift surveys alone, and that in some cases the addition of further data from high-density peculiar velocity surveys is more successful at overcoming the sample variance than adding further data from redshifts only. We demonstrate that it may be possible to achieve upper bounds of ∑mν ≈ 0.14 eV (68 per cent confidence limit), from upcoming spectroscopic galaxy surveys alone, as long as the peculiar velocity data is available, an improvement of ∼14 per cent over redshift surveys alone, but not as strong as when CMB data are included.