Could intergalactic dust obscure a neutrino decay signature?

Following recent results from the Super-Kamiokande experiment which indicat e that neutrinos may have finite masses and provide at least part of the da rk matter in the Universe, we re-examine the decaying neutrino hypothesis o f Sciama, including for the first time the effects of absorption by interga lactic dust. We consider several dust models, including one designed to opt imize ultraviolet extinction for a given dust-to-gas ratio. Dust absorption is insufficient to reconcile the theory with observational upper limits on the intensity of the diffuse ultraviolet background reported recently by M urthy et al. The theory remains marginally compatible with other diffuse ba ckground measurements.