Modifying PyUltraLight to model scalar dark matter with self-interactions

Understand

We introduce a modification of the PyUltraLight code that models the dynamical evolution of ultralight axionlike scalar dark matter fields.

• Our modified code, PySiUltraLight, adds a quartic, self-interaction term to reflect the one which arises naturally in axionlike particle models.
• Using a particle mass of $10^{-22}~\mathrm{eV}/\mathrm{c}^2$, we show that PySiUltraLight produces spatially oscillating solitons, exploding solitons, and collapsing solitons which prior analytic work shows will occur with attractive self-interactions.
• Using our code we calculate the oscillation frequency as a function of soliton mass and equilibrium radius in the presence of attractive self-interactions.