WIDG Seminar: Luna Zagorac, Yale, “Linear Approximations to UltraLight Dark Matter Stationary States”

Event time: 
Wednesday, May 12, 2021 - 3:00pm to 4:00pm

Event description: 

UltraLight Dark Matter (ULDM) is an axion-like dark matter candidate with an extremely small particle mass. The dynamics of ULDM are governed by the Schrodinger-Poisson system of coupled differential equations for which the ground state solution is a spherically symmetric soliton. While a purely solitonic profile is incompatible with observational constraints on dark matter halos, mergers of ULDM solitons create halos with solitonic central cores, but with NFW-like behaviour at large radii. In this talk I will present how we 1) generate eigenstates of the system, 2) simulate the behavior of the ground state when perturbed by a single higher order state and 3) compare those simulations with linear perturbation theory predictions. I will use the comparison of simulation and linear theory to illustrate qualitative effects seen in ULDM simulations, including the soliton “breathing mode,” and show that these effects have a basis in theory. Finally, I will show a simulation of a ULDM halo forming through a merger of eight solitons and its decomposition into constituent eigenstates. This system doesn’t tend to a late stage “relaxed” halo, but rather that new modes are constantly excited and de-excited in a complex pattern, making perturbation theory intractable for such a formation mechanism.
Host: Giacomo Scanavini