What is JWST telling us about cosmology?

by Julian Muñoz (University of Texas)

Monday 18 Dec 2023, 12:00 → 13:00 Europe/Madrid

IFAE Seminar Room (In-person Seminar)

The launch of the James Webb Space Telescope (JWST) has ignited a revolution in our understanding of the early universe. Its exquisite infrared capabilities have allowed observers to measure the stellar masses of galaxies, as well as to find them at higher redshifts than ever before. I will describe how, intriguingly, observations in these two arenas appear to be in tension with our models. First, I will discuss the ultra-massive galaxy candidates recently argued to “break” our cosmological model (LCDM). We used HST observations at the same redshifts to rule out the required departures from LCDM, disfavoring a cosmological solution. Then, I will discuss the higher-than-expected abundance of z>10 galaxies in JWST. This issue has two astrophysical solutions, and I will show how high-z galaxy clustering can distinguish between them, breaking degeneracies in the first galaxies.