HYBRID TALK| Hee-Jong Seo “Accelerating Universe through DESI”

Abstract

One of the most intriguing questions in physics today is the nature of dark energy that is responsible for the accelerated expansion of the Universe. Three-dimensional maps of galaxies from spectroscopic galaxy surveys provide a giant laboratory to test the nature of the Universe, including dark energy, in a way that is complementary to other cosmic surveys. DESI, being the largest galaxy redshift survey up to date, is currently preparing for the first-year cosmology analysis release in Summer 2023, In this talk, among the key science goals of DESI,  I want to focus on the studies of two accelerated expansion phases of the Universe using DESI, one today due to dark energy and the other, cosmic inflation right after the Big Bang. For the former, I will show the first Baryon Acoustic Oscillation detection result using only the first two months of the DESI data. For the latter, I will discuss how we can fight the observational systematics using neural networks and derive a tight constraint on inflation using the DESI Legacy survey.