Seeing double: strong gravitational lensing of high-redshift supernovae

Abstract

With the advent of large, deep surveys, the observation of a strongly gravitationally lensed supernova becomes increasingly likely. High-redshift surveys continue apace, with a handful of type Ia supernovae observed to date at redshifts of one or greater. In addition, a satellite (the Supernova/Acceleration Probe [SNAP]) has been proposed dedicated to observing thousands of supernovae per year out to a redshift of 1.7. Although it is exceedingly unlikely that we will see a multiply-imaged supernova from ongoing surveys, we find that SNAP would observe at least eight such events per year. Since having a standard candle is inessential to most lensing studies, SNAP's large sample of type II supernovae contributes to this rate. Each case of strong lensing allows for a precise determination of time delays, image separations, and relative image magnifications, and the SNAP strong-lensing database will offer measures of $Ω_m$, $Ω_Λ$, and $H_0$, independent of SNAP's primary goal of establishing the distance-redshift relation. These systems also constrain models for the matter density profiles of galaxies and clusters. Furthermore, lensed type Ia supernovae afford the opportunity to break the mass-sheet degeneracy found in many lensing measurements.