Jiaming Pan is a Ph.D. candidate in Physics at the University of Michigan. His research focuses on constraining modified gravity and dark energy to understand the physical origin of cosmic acceleration. He is an active member of the Dark Energy Spectroscopic Instrument (DESI) collaboration, where he has contributed to analyses of dark energy and tests of gravity, including extended dark energy analysis with BAO measurements and modified gravity constraints from full-shape clustering. He is also developing methods to use gravitational-wave “standard sirens,” particularly through cross-correlation with galaxy surveys, as independent probes of the Hubble constant.
Title: Constraining Modified Gravity and Dark Energy with DESI
Abstract: Recent findings from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2) suggest that dark energy is not behaving as a cosmological constant but may be dynamical with a phantom-crossing feature. In this talk, I will show how these trends can be interpreted as hints of modifications to Einstein’s theory of gravity on cosmological scales. Using a model-independent EFT framework, I will present constraints on non-minimal coupling between matter and gravity, providing a late-universe test of modified gravity. Finally, I will outline future directions for testing modified gravity, including the use of theory-consistent initial conditions and Einstein–de Sitter extensions for full-shape analyses.