Updated Parameters for the Decaying Neutrino Theory and EURD Observations of the Diffuse UV Background

Various recent observational developments are here used to make a more critical analysis of the parameter space of the decaying neutrino theory for the ionisation of the interstellar medium. These developments involve phenomena inside our Galaxy, outside the Galaxy but at essentially zero red shift, and at large red shifts. This new analysis leads to a viable theory with a decay lifetime of $2{\pm}1\times 10^{23}$ sec, a decay photon energy of $13.7{\pm}0.1$ eV, and a mass for the decaying neutrino of $27.4 {\pm}0.2$ eV. These parameters, when combined with some known astronomical quantities, lead to predictions for the intensity, the wavelength and the width of the decay line produced by neutrinos lying within one optical depth of the sun $({\sim} 1/2 pc)$. One finds an intensity in the line of $350^{+350}_{-117}$ photons $cm^{-2} sec^{-1}$, a wavelength of $905\pm7\AA$, and a width $\sim1\AA$. These predictions are relevant for the observations about to be made by the EURD ultra-violet detector which is currently in Earth orbit on board the Spanish MINISAT 01 satellite.