The 38th Ockham Lecture - ‘Chasing Cosmic Dawn with the James Webb Space Telescope’

Given by Professor Charlotte Mason, Merton College (MPhys 2013) Associate Professor, Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen.

Abstract

There is a missing chapter in our Universe's history: when and how did the first stars and galaxies form? The first stars drove the Universe's final phase transition by heating and ionising intergalactic gas, setting the stage for all subsequent structure formation. Until recently this has been the realm of theorists alone, but, with the launch of the James Webb Space Telescope (JWST) in December 2021, our observational horizon has expanded to the first few hundred million years after the Big Bang. JWST is the largest telescope ever launched into space and was designed to observe directly this period of "Cosmic Dawn", using atomic-hydrogen transitions to search for the first galaxies. Excitingly, JWST has discovered a large number of bright galaxies in the early Universe, implying galaxy formation may have proceeded very differently than expected by theoretical models. I will review our current picture of galaxy formation and how it is being tested by JWST. I will describe possible explanations for the new observations and prospects for JWST to distinguish between these scenarios and to help us understand the primary physics driving the formation of the first galaxies.

The Ockham Lecture Series

The Merton College Physics Lecture (the Ockham, or Occam, Lecture, so named in honour of one of the greatest—if unattested—alumni of the College and of his philosophical principle of intellectual discipline) started in 2009 and is held once a term. It is organised by the physics tutors of the College to promote both intellectual curiosity and social cohesion of the Merton Physics community.