Dr. Kay Kirkpatrick (Dept. of Mathematics, Univ. of Illinois Urbana-Champaign)

11/8/21  4:10pm

Abstract:

Dark matter, which has no color but rather is transparent, makes up probably a quarter of the energy-matter density of our universe. Gravitational lensing and cosmic microwave background fluctuations suggest that dark matter cannot be explained away by just modifying gravity. One model for dark matter is the hypothetical quantum particle that solves the strong Charge+Parity problem in quantum chromodynamics: the axion.

Clusters of axions probably formed in the early universe, with their cores condensing into ultra-cold Bose-Einstein condensates (BEC) that have macroscopic quantum properties. For axion clusters the size of a star or a galaxy, the mathematical description is a pair of equations: the non-linear Schr\"odinger (NLS) equation for self-interactions, and the Poisson or Newton equation for interactions through gravity. In work with Anthony Mirasola and Chanda Prescod-Weinstein, we use an approach based on the Wigner distribution to study the NLS-Poisson system and calculate that the condensation of axions into a BEC is driven by gravity and should be possible within the lifetime of our universe.