EDP Sciences
Planck 2015 results
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Fig. 32


Samples from Planck TT+lowP in the Neff plane, colour-coded by σ8, for models with one massive sterile neutrino family, with effective mass , and the three active neutrinos as in the base ΛCDM model. The physical mass of the sterile neutrino in the thermal scenario, , is constant along the grey dashed lines, with the indicated mass in eV; the grey shading shows the region excluded by our prior , which cuts out most of the area where the neutrinos behave nearly like dark matter. The physical mass in the Dodelson-Widrow scenario, , is constant along the dotted lines (with the value indicated on the adjacent dashed lines).