Massive galaxy clusters as gravitational telescopes for distant   supernovae
  We investigate the potential of using massive clusters as gravitational telescopes for searches and studies of supernovae of Type Ia and Type II in optical and near-infrared bands at central wavelengths in the interval 0.8-1.25 microns. Using high-redshift supernova rates derived from the measured star formation rate, we find the most interesting effects for the detection of core-collapse SNe in searches at limiting magnitudes m_lim~25-26.5 mag, where the total detection rate could be significantly enhanced and the number of detectable events is considerable even in a small field. For shallower searches, ~24, a net gain factor of up to 3 in the discovery rate could be obtained, and yet a much larger factor for very high source redshifts. For programs such as the GOODS/ACS transient survey, the discovery rate of supernovae beyond z~2 could be significantly increased if the observations were done in the direction of massive clusters. For extremely deep observations, m_lim > 27 mag, or for very bright SNe (e.g. Type Ia) the competing effect of field reduction by lensing dominates, and fewer supernovae are likely to be discovered behind foreground clusters. 
Christofer Gunnarsson and Ariel Goobar (Stockholm University)