Detecting strongly lensed supernovae at z ~ 5-7 with LSST

TL;DR

This paper evaluates LSST's potential to detect high-redshift strongly lensed supernovae (z ~ 5-7), highlighting the importance of gravitational lensing in observing early universe supernovae.

Contribution

It provides the first detailed estimates of detection rates for lensed supernovae at high redshifts with LSST, considering various survey strategies and supernova populations.

Findings

LSST could detect up to 120 lensed Pop I/II supernovae at z ~ 5-7.

Deep-drilling surveys can detect Pop I/II and Pop III supernovae at AB magnitudes of 26-28.

An 80-night deep survey could find approximately 8 Pop III supernovae.

Abstract

Supernovae (SNe) could be powerful probes of the properties of stars and galaxies at high redshifts in future surveys. Wide fields and longer exposure times are required to offset diminishing star formation rates and lower fluxes to detect useful numbers of events at high redshift. In principle, the Large Synoptic Survey Telescope (LSST) could discover large numbers of early SNe because of its wide fields but only at lower redshifts because of its AB mag limit of ~ 24. But gravitational lensing by galaxy clusters and massive galaxies could boost flux from ancient SNe and allow LSST to detect them at earlier times. Here, we calculate detection rates for lensed SNe at z ~ 5 - 7 for LSST. We find that the LSST Wide Deep Fast survey could detect up to 120 lensed Population (Pop) I and II SNe but no lensed Pop III SNe. Deep-drilling programs in a single 10 square degree FoV could detect Pop I and II core-collapse SNe and Pop III pair-instability SNe at AB magnitudes of 27 - 28 and 26, respectively. An alternative deep survey over 80 nights with a one-year cadence could find ~ 8 Pop III SNe.