Limit on the frequency of intergalactic supernovae

The observation that there are 'no intergalactic supernovae' is discussed with respect to the Coma cluster of galaxies. In this cluster, where at least 30% of the total luminosity lies outside the regions normally associated with individual galaxies, the absence of intergalactic supernovae can be used to derive restrictions on the nature of the luminous intergalactic material, whether it be a diffuse collection of stars, a background of low surface brightness dwarf galaxies, or some other form of luminous matter. From the discussion it is concluded that the intergalactic medium is deficient in supernova progenitors by a factor of >= 5. (author)