Observing high-redshift supernovae in lensed galaxies

Supernovae in distant galaxies that are gravitationally lensed by foregroun d galaxy clusters make excellent standard candles for measuring cosmologica l quantities like the density of the Universe in its various components and the Hubble constant. Distant supernovae would be rendered more easily dete ctable in the fields of rich galaxy clusters since the latter could act as foreground lenses, magnifying such supernovae by up to 3-4 magnitudes. We s how that in the case of the lens cluster Abell 2218, the detectability of h igh-redshift supernovae is significantly enhanced due to the lensing effect s of the cluster. The signal-to-noise ratio for the observation of lensed s upernovae will be further enhanced, typically by an order of magnitude, sin ce they will remain point images even when their host galaxies are stretche d into arcs by the effect of lensing. We recommend monitoring with medium-s ized telescopes well-modelled clusters with several known arclets for the d etection of cosmologically useful SNe around z = 1 and beyond.