Cosmic core-collapse supernovae from upcoming sky surveys

Abstract

Large synoptic (repeated scan) imaging sky surveys are poised to observe enormous numbers of core-collapse supernovae. We quantify the discovery potential of such surveys, and apply our results to upcoming projects, including DES, Pan-STARRS, and LSST. The latter two will harvest core-collapse supernovae in numbers orders of magnitude greater than have ever been observed to date. These surveys will map out the cosmic core-collapse supernova redshift distribution via direct counting, with very small statistical uncertainties out to a redshift depth which is a strong function of the survey limiting magnitude. This supernova redshift history encodes rich information about cosmology, star formation, and supernova astrophysics and phenomenology; the large statistics of the supernova sample will be crucial to disentangle possible degeneracies among these issues. For example, the cosmic supernova rate can be measured to high precision out to z ∼ 0.5 for all core-collapse types, and out to redshift z ∼ 1 for Type IIn events if their intrinsic properties remain the same as those measured locally. A precision knowledge of the cosmic supernova rate would remove the cosmological uncertainties in the study of the wealth of observable properties of the cosmic supernova populations and their evolution with environment and redshift. Because of the tight link between supernovae and star formation, synoptic sky surveys will also provide precision measurements of the normalization and z ⪅ 1 history of cosmic star-formation rate in a manner independent of and complementary to than current data based on UV and other proxies for massive star formation. Furthermore, Type II supernovae can serve as distance indicators and would independently cross-check Type Ia distances measured in the same surveys. Arguably the largest and least-controlled uncertainty in all of these efforts comes from the poorly-understood evolution of dust obscuration of supernovae in their host galaxies; we outline a strategy to determine empirically the obscuration properties by leveraging the large supernova samples over a broad range of redshift. We conclude with recommendations on how best to use (and to tailor) these galaxy surveys to fully extract unique new probes on the physics, astrophysics, and cosmology of core-collapse explosions.