AX-GADGET: a new code for cosmological simulations of Fuzzy Dark Matter and Axion models

TL;DR

This paper introduces AX-GADGET, a new parallel N-Body simulation code for Fuzzy Dark Matter that accurately models quantum effects without sacrificing performance, enabling better exploration of FDM's role in cosmic structure formation.

Contribution

The paper presents a novel module for P-GADGET3 that efficiently incorporates Quantum Potential effects in FDM simulations, improving accuracy and stability over previous methods.

Findings

Validated QP's role in small-scale structure suppression

Demonstrated code's accuracy against analytical and other simulation results

Enabled comprehensive FDM model exploration with existing physics modules

Abstract

We present a new module of the parallel N-Body code P-GADGET3 for cosmological simulations of light bosonic non-thermal dark matter, often referred as Fuzzy Dark Matter (FDM). The dynamics of the FDM features a highly non-linear Quantum Potential (QP) that suppresses the growth of structures at small scales. Most of the previous attempts of FDM simulations either evolved suppressed initial conditions, completely neglecting the dynamical effects of QP throughout cosmic evolution, or resorted to numerically challenging full-wave solvers. The code provides an interesting alternative, following the FDM evolution without impairing the overall performance. This is done by computing the QP acceleration through the Smoothed Particle Hydrodynamics (SPH) routines, with improved schemes to ensure precise and stable derivatives. As an extension of the P-GADGET3 code, it inherits all the additional physics modules implemented up to date, opening a wide range of possibilities to constrain FDM models and explore its degeneracies with other physical phenomena. Simulations are compared with analytical predictions and results of other codes, validating the QP as a crucial player in structure formation at small scales.