JWST's First Glimpses of Early Galaxies and Implications for Cosmology

One of the main suprises of JWST has been the discovery of an abundant population of bright galaxies at z>10, when the universe was only 500 million years old. The number density of these galaxies vastly exceeds pre-JWST estimates based on Hubble data and empirical models, questioning our understanding of early star formation and dust production mechanisms. Some authors have suggested that this population may even be difficult to reconcile with standard cosmology. In addition, JWST has discovered an abundant population of active supermassive black holes in the pre-ionization era, suggesting that their build-up is accelerated with respected to prior understanding. Producing such high mass black holes in just a few hundred million years is difficult assuming traditional growth mechanisms from stellar remnants, and it has been argued that the so-called direct collapse mechanism is favored by the observations. I will present a critical review of JWST results on these topics and discuss their implications for our understanding of the formation of cosmic structures, cosmic reionization, and cosmology.