Event Details

Speaker: Prof. Ariel Goobar -Oskar Klein Centre, Department of Physics, Stockholm University, Sweden Refreshments served afterwards in Physics Building C036

Abstract

Einstein’s theory of General Relativity predicts that light is deflected by space-time curvature. The rare cases where a distant astronomical source is aligned with a massive foreground object can result in significant enhancement of the source flux. This phenomenon, known as gravitational lensing, can be used to study distant faint objects, otherwise beyond instrumental sensitivity, as well as the properties of the lenses, i.e., stars, galaxies and clusters of galaxies. For large lensing magnifications, the light gets deflected into multiple images. This is particularly interesting when the lensed source is transient, e.g., a supernova explosion. The difference in arrival time between the multiple images can be used to infer the Hubble constant, arguably the most contested parameter in cosmology today.

Recent observational breakthroughs leading to the discovery of multiply-imaged supernovae will be discussed. An intriguing realization is that supernova surveys, even from ground-based astronomical facilities unable to resolve the multiple images, can identify gravitational lensing systems missed by other techniques. This makes lensed supernovae an interesting tool to explore the density profile, stellar composition (including black holes) and interstellar medium in the densest regions of galaxies.

About the speaker

Ariel Goobar is the Professor of Physics Department, Stockholm University and Director of Oskar Klein Centre for Cosmoparticle Physics. Prof. Ariel Goobar is one of the pioneers of the Type Ia supernova cosmology and is a co-author of 2011 Nobel Prize paper on discovery of the accelerating universe. He received many prizes and honours. He was a member of the Nobel Committee for Physics 2019 and 2020.

Teams Link: https://teams.microsoft.com/l/meetup-join/19%3a733e16cef012444196c8ad9fd91e46c1%40thread.tacv2/1709560402398?context=%7b%22Tid%22%3a%229c9bcd11-977a-4e9c-a9a0-bc734090164a%22%2c%22Oid%22%3a%220749b30f-f4ab-4f3b-bbb8-c219ad795e86%22%7d