Decaying neutrinos and the nature of the dark matter in galaxy clusters

It is widely believed that Sciama's (1990) decaying-neutrino theory has been disproved by the failure of Davidsen et al. (1991) to detect an unidentified emission line at approximately 15 eV (in the rest frame) from the dark matter in the cluster of galaxies A665 (e.g., Trimble 1992). Here we show that recent X-ray data for A665 favor models in which the dark matter in the regions of the cluster observed by Davidsen et al. is mainly baryonic. Thus the decaying-neutrino theory continues to be viable.