Phantom of RAMSES (POR): A new Milgromian dynamics N-body code

TL;DR

This paper introduces Phantom of RAMSES (POR), a new N-body simulation code based on RAMSES, designed to explore Milgromian dynamics (MOND) in galaxy models with high resolution and direct comparison to Newtonian simulations.

Contribution

It presents a customized RAMSES-based N-body code for Milgromian dynamics, enabling detailed simulations of galaxy systems with adaptive mesh refinement.

Findings

Successfully tested the code with spherical equilibrium models.

Simulated dark-matter-free disk galaxies in Milgromian dynamics.

Demonstrated high spatial resolution and performance of the code.

Abstract

Since its first formulation in 1983, Milgromian dynamics (MOND) has been very successful in predicting the gravitational potential of galaxies from the distribution of baryons alone, including general scaling relations and detailed rotation curves of large statistical samples of individual galaxies covering a large range of masses and sizes. Most predictions however rely on static models, and only a handful of N-body codes have been developed over the years to investigate the consequences of the Milgromian framework for the dynamics of complex evolving dynamical systems. In this work, we present a new Milgromian N-body code, which is a customized version of the RAMSES code (Teyssier 2002) and thus comes with all its features: it includes particles and gas dynamics, and importantly allows for high spatial resolution of complex systems due to the adaptive mesh refinement (AMR) technique. It further allows the direct comparison between Milgromian simulations and standard Newtonian simulations with dark matter particles. We provide basic tests of this customized code and demonstrate its performance by presenting N-body computations of dark-matter-free spherical equilibrium models as well as dark-matter-free disk galaxies in Milgromian dynamics.