JWST’s GLIMPSE: A view of the faintest galaxies in the first billion
years of cosmic time

Speaker : John Chisholm The University of Texas at Austin

Abstract :

Faint high-redshift galaxies in the early universe constrain the properties of
dark matter, the early build-up of stellar mass, and which sources reionized
the early universe. The first two years of JWST observations have revealed
a wealth of constraints on modestly bright galaxies in the first billion years
of cosmic time, but the faintest population has remained under-probed.
JWST’s Glimpse is a Cycle 2 large program that pairs up to 39 hour
integrations with the natural lensing of the massive foreground cluster Abell
S1063. These observations probe a new regime of intrinsically faint
galaxies (down to MUV of -10 or observed magnitudes of 34) in the early
universe. With seven wide and two medium bands, we find a new class of
galaxy candidates within the first 200 Myr of cosmic time that must have
formed extremely efficiently. We also constrain the number of very faint
galaxies in Cosmic Dawn, the star formation histories of early galaxies, and
explore how the faintest galaxies contributed to reionization.
In this talk I will highlight our preliminary effort to reveal the population
of the faintest early galaxies and their impact on the evolution of the
universe.