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Astro Seminar

Gravitationally lensed supernovae: Finding the needle in the haystack

Speaker: Mark Magee (ICG Portsmouth)
Date: Wednesday 9 November 2022
Time: 14:00
Venue: N3.28/Zoom

Measurements of the Hubble constant from the early and late Universe are in disagreement at approximately a five sigma level. This is one of the most puzzling open questions in modern astrophysics and independent verification of existing measurements is needed to unravel this mystery. A promising method for doing so is through the use of gravitationally lensed supernovae, which occur when a sufficiently massive foreground galaxy distorts spacetime to such an extent that multiple images of any background source are formed. To date however, only a handful of confirmed or candidate lensed supernovae are known. In this talk I will detail our current understanding of gravitationally lensed supernovae, including our search within the public survey of the Zwicky Transient Facility. I will show how various selection criteria proposed in the literature affect the identification of candidate objects and discuss sources of contamination. Correct identification of candidates and contaminants will become increasingly important for future surveys, such as LSST, which will likely discover hundreds of lensed supernovae in the coming years.