Self-Interaction Controls Vortex Scale in Soliton Mergers

This study investigates the impact of self-interaction strength on the formation and scale of turbulent vortex structures during the merger of Bose stars, using numerical simulations of the Gross-Pitaevskii-Poisson (GPP) equations. We find that vortex formation is a universal outcome of soliton mergers, with the vortex size strongly dependent on the self-interaction coupling parameter $g$. Through analysis of velocity correlations, kinetic energy spectra, and vorticity distributions, we conclude that for repulsive self-interaction, the vortex region expands as self-interaction strength increases; conversely, for attractive self-interaction, the vortex region shrinks as self-interaction strength increases.