CMB neutrino mass bounds and reionization

Current cosmic microwave background bounds on the sum of the neutrino masses assume a sudden reionization scenario described by a single parameter that determines the onset of reionization. We investigate the bounds on the neutrino mass in a more general reionization scenario based on a principal component approach. We found the constraint on the sum of the neutrino masses from cosmic microwave background data can be relaxed by ∼40% in a generalized reionization scenario. Moreover, the amplitude of the rms mass fluctuations σ8 is also considerably lower providing a better consistency with the low amplitude of the Sunyaev-Zel'dovich signal recently found by the South Pole Telescope.