2015 New Initiative Grant
Justin Khoury, Ph.D. (PI) Associate Professor, Physics, Associate Chair for Undergraduate Affairs, University of Pennsylvania
Tom Lubensky (co-PI) Christopher H. Brown Distinguished Professor of Physics, University of Pennsylvania
New Approach to Dark Matter
Despite the overwhelming evidence of its existence, the underlying nature of dark matter remains a mystery. The proposed new initiative brings together concepts of theoretical condensed matter physics, cold atom physics and astrophysics to develop a novel framework for dark matter. This is motivated by a number of puzzles on the scales of galaxies that have emerged in recent years. These puzzles, together with the persistent failure of increasingly sensitive experiments to detect the elusive dark matter particle, offer a compelling case that the physics of dark matter may be richer than hitherto anticipated. The proposed approach capitalizes on the rich and well-studied physics of superfluidity. We propose that dark matter forms a superfluid in galaxies. The sound waves associated with the superfluid interact with stars and gas in the galaxy and affect their orbital motion. This results in a modified gravitational force law mimicking Modified Newtonian Dynamics (MOND), an empirical framework that does exquisitely well at explaining the observed properties of galaxies. We propose two main lines of inquiry. The first major research direction is to seek a deeper understanding of dark matter superfluidity by applying techniques and concepts of condensed matter theory to the problem at hand. The second major research direction is to fully develop the observational predictions that can distinguish dark matter superfluidity from the standard gaseous phase of dark matter particles.