High-redshift supernova rates measured with the gravitational telescope A 1689
Dahle, H.; Lidman, C.; Amanullah, R.; Fabbro, S.; Goobar, A.; Nordin, J.; Johansson, J.; Richard, J.; Kneib, J. P.; Stanishev, V.; Limousin, M.; Paech, K.; Petrushevska, T.; Ferretti, R.; Kjellsson, T.
Sweden, Canada, Israel, Australia, Germany, France, Norway, Switzerland
Abstract
Aims: We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z = 0.18, which is one of the most powerful gravitational telescopes that nature provides.
Methods: Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data from the Nordic Optical Telescope.
Results: Our search resulted in the discovery of five photometrically classified, core-collapse supernovae with high redshifts of 0.671 < z < 1.703 and magnifications in the range Δm = - 0.31 to -1.58 mag, as calculated from lensing models in the literature. Owing to the power of the lensing cluster, the survey had the sensitivity to detect supernovae up to very high redshifts, z 3, albeit for a limited region of space. We present a study of the core-collapse supernova rates for 0.4 ≤ z< 2.9, and find good agreement with previous estimates and predictions from star formation history. During our survey, we also discovered two Type Ia supernovae in A 1689 cluster members, which allowed us to determine the cluster Ia rate to be 0.14+0.19-0.09±0.01SNuB h2 (SNuB≡10-12SNe L-1⊙,B yr-1), where the error bars indicate 1σ confidence intervals, statistical and systematic, respectively. The cluster rate normalized by the stellar mass is 0.10+0.13-0.096±0.02 in SNuM h2 (SNuM ≡10-12SNe M-1⊙ yr-1). Furthermore, we explore the optimal future survey for improving the core-collapse supernova rate measurements at z ≳ 2 using gravitational telescopes, and for detections with multiply lensed images, and we find that the planned WFIRST space mission has excellent prospects.
Conclusions: Massive clusters can be used as gravitational telescopes to significantly expand the survey range of supernova searches, with important implications for the study of the high-z transient Universe.