The distribution of dark matter in galaxies. II. Neutrino-mass limits

If the dark matter in galaxies is composed of one flavor of neutrino, its distribution sets a lower limit to the neutrino mass. To use this constraint, the distribution of dark matter must be modeled. It is shown here that, when models are constructed, the neutrino mass must exceed 19 eV. The dwarf galaxy DDO 154 suggests higher mass limits, but the results are dominated by uncertainties in the distance and the amount of gas in the system. The distribution of dark matter in galaxies currently places no serious constraint on the picture that neutrinos are the dark matter. An additional discriminant between warm and cold dark matter is proposed, namely, the variation of phase density with luminosity. 38 refs