Beyond the Hubble Frontier: How JWST is Shaping Our
Understanding of the Early Universe ?

Speaker : Nicolas Laporte

Abstract :

The launch of the James Webb Space Telescope (JWST) in late 2021 has
marked the beginning of a new era in extragalactic science, opening the
door to a golden age of discovery. In its first months of operation, JWST
has already revolutionized our understanding of the early Universe.
Pushing observational limits further back in time than ever before, it has
captured galaxies as early as ~300 million years after the Big Bang,
surpassing the previous threshold of ~400 million years set by the Hubble
Space Telescope (HST). These transformative observations not only
expand our knowledge but also challenge the foundations of the current
cosmological model, the Lambda-CDM paradigm. Key discoveries include:
(i) the detection of galaxies more massive than previously believed
possible; (ii) the compact nature of primordial galaxies; (iii) the unexpected
abundance of Active Galactic Nuclei (AGN) in the early Universe; and (iv)
the identification of protoclusters—large-scale structures hosting galaxies
with AGN activity at their cores. These findings are reshaping our
understanding of cosmic dawn. In this seminar, I will first review the most
exciting discoveries made by JWST, then focus on the first constraints on
early large-scale structures, and conclude by discussing the role that future
instruments on the Extremely Large Telescope (ELT) will play in advancing
our understanding of the formation and evolution of the first galaxies.