Astrophysics Colloquium: Fundamental Physics from Near-Field Cosmology

Abstract:  The current era of precision cosmology has revealed just how little we understand about the major components that drive the evolution of the universe: dark energy, dark matter, neutrinos, and inflation. In order to better understand the fundamental physics that governs the behavior of the universe, we must continue to improve our instruments and measurements. One of the frontiers of precision cosmology involves measuring the cosmological distribution of matter on smaller and smaller length scales. Small scales are relatively unexplored and are sensitive to the fundamental physics of dark matter and inflation. On these scales, dark matter clusters into gravitationally bound systems known as halos. Since the visible systems that inhabit the smallest known dark matter halos are extremely faint, they are most easily studied in the local universe. This is the domain of near-field cosmology.I will discuss what we have learned about fundamental physics from near-field cosmology over the last decade, and I will look ahead to the exciting era of discovery expected from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST). Wide-fast-deep imaging by Rubin LSST is poised to confirm or invalidate one of the core predictions of the conventional cosmological model: the existence of low-mass dark matter halos that lack baryons. Furthermore, Rubin LSST is a gateway to a broader experimental program to use astrophysical observations to better understand the fundamental nature of dark matter, and more broadly, the fundamental physics that governs the clustering of matter at extremely small scales.