Julian Muñoz

What is JWST teaching us about the early Universe?

The James Webb Space Telescope (JWST) is revolutionizing our understanding of the early universe, and in this talk I will explore how its observations fit — or don’t — within our cosmological and galaxy-formation models. First, I will discuss the unexpectedly high abundance of galaxies in the first few hundred million years of cosmic history (redshift z>9), and how to use cosmological clustering measurements to understand its origin. Then, I will show that current data can put tight constraints on the amount of star-formation variability, the timescales involved, and how it varies with halo mass. Finally, I will examine how recent JWST determinations of cosmic reionization may be at odds with complementary cosmological probes, including the CMB and the Lyman-alpha forest, and will discuss implications for cosmology, astrophysics, and the 21-cm signal.