Dark Matter Self-interactions: Bridging Perspectives from Cosmology and Astrophysics

Synopsis

There is a wealth of evidence that our universe contains an invisible mass/energy content which behaves just like regular matter. We can't see or feel it. We can observe the presence of this "Dark Matter" (DM) through its gravitational effects, but despite enormous efforts, we cannot observe DM directly. Physicists study DM across a broad range of scales, from the effect it has on the expansion of the universe, down to its influence on galaxy dynamics. These different scales lend themselves to very different tools and frameworks for understanding DM. On the largest scales, cosmologists consider what (if any) additional long-range forces, like electromagnetism, might apply to DM. At smaller scales, observations show some preference for scattering interactions between pairs of DM particles.

Despite the vastly different scales of these two descriptions, there is an overlap in the fundamental physics descriptions of astroparticle DM scattering, and cosmological additional forces. Uncovering the phenomenological behaviour of DM helps inform the direction of future DM detection experiments, which will ultimately lead to detection and subsequent study of DM. In this talk I will introduce the motivation for DM interactions in both regimes and discuss my work in bridging the gap to unify these two descriptions of DM interaction dynamics. I will discuss when cosmological constraints become of interest to astro-particle physicists, and what sorts of models are phenomenologically interesting to both groups.