The Effect of Boundary Conditions on Structure Formation in Fuzzy Dark Matter

Abstract

We illustrate the effect of boundary conditions on the evolution of structure in Fuzzy Dark Matter. Scenarios explored include the evolution of single, ground-state equilibrium solutions of the Schrödinger-Poisson system, the relaxation of a Gaussian density fluctuation, mergers of two equilibrium configurations, and the random merger of many solitons. For comparison, each scenario is evolved twice, with isolation boundary conditions and periodic boundary conditions, the two commonly used to simulate isolated systems and structure formation, respectively. Replacing isolation boundary conditions by periodic boundary conditions changes the domain topology and dynamics of each scenario, by affecting the outcome of gravitational cooling. With periodic boundary conditions, the ground-state equilibrium solution and Gaussian fluctuation each evolve toward the single equilibrium solitonic core of the isolated case, but surrounded by a tail, unlike the isolated versions. The case of head-on, binary mergers illustrates additional effects, caused by the pull suffered by the system due to the infinite network of periodic images along each direction of the domain. Binary merger with angular momentum is the first scenario we found in which the tail has a polynomial profile when using a periodic domain. Finally, the 3D merger of many, randomly-placed solitonic cores of different mass makes a solitonic core surrounded by a tail with power-law-like density profile, for periodic boundary conditions, while producing a core with a much sharper fall-off in the isolated case. This suggests that the conclusion of earlier work that the ground-state equilibrium solution is an attractor for the asymptotic state is true even in 3D and for general circumstances, but only if gravitational cooling is able to carry mass and energy off to infinity, which isolation boundary conditions allow, but periodic ones do not.

17 pages, 18 figures, modifications applied in order to match the accepted version in Phys. Rev. D

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• Solitons and halos for self-interacting scalar dark matter
• Spherical solutions of the Schrödinger-Poisson system with core-tail structure
• Fermion-Boson Stars as Attractors in Fuzzy Dark Matter and Ideal Gas Dynamics
• Single and merger soliton dynamics in scalar field dark matter with and without self-interactions
• Kinematic Imprints of vortex-lines of BEC Dark Matter on Baryonic Matter
• Black Holes as Condensation Points of Fuzzy Dark Matter Cores
• Dynamical friction in ultralight dark matter: Plummer sphere perspective
• Dynamical reconstruction of SPARC galactic halos within self-interacting fuzzy dark matter
• Unveiling Orbital Chaos: The Wild Heart of Fuzzy Dark Matter Structures
• Equilibrium Core and Vortex Solutions of Bose Einstein Condensate Dark Matter around a Black Hole
• Temporal Correlations Between Fuzzy Dark Matter and Baryonic Matter in Virialized Core-Halo Structures
• Effects of Self-Interaction and of an Ideal Gas in Binary Mergers of Bosonic Dark Matter Cores
• Time-dependent adaptive mesh refinement solver for the Gross-Pitaevskii-Poisson equations