Investigating the influence of magnetic fields upon structure formation with AMIGA - a C code for cosmological magnetohydrodynamics

TL;DR

This paper introduces AMIGA, a new numerical code combining N-body and MHD solvers to simulate the impact of primordial magnetic fields on cosmic structure formation, finding that realistic magnetic field strengths have limited influence.

Contribution

The paper presents AMIGA, a novel cosmological MHD simulation code that accurately models magnetic fields, dark matter, and baryons in a self-consistent framework.

Findings

Primordial magnetic fields need to be stronger than current constraints to significantly affect large-scale structure.

AMIGA demonstrates high accuracy in capturing shocks and supersonic flows in cosmological MHD simulations.

Simulations show limited impact of realistic primordial magnetic fields on matter distribution.

Abstract

Despite greatly improved observational methods, the presence of magnetic fields at cosmological scales and their role in the process of large-scale structure formation still remains unclear. In this paper we want to address the question how the presence of a hypothetical primordial magnetic field on large scales influences the cosmic structure formation in numerical simulations. As a tool for carrying out such simulations, we present our new numerical code AMIGA. It combines an N-body code with an Eulerian grid-based solver for the full set of MHD equations in order to conduct simulations of dark matter, baryons and magnetic fields in a self-consistent way in a fully cosmological setting. Our numerical scheme includes effective methodes to ensure proper capturing of shocks and highly supersonic flows and a divergence-free magnetic field. The high accuracy of the code is demonstrated by a number of numerical tests. We then present a series of cosmological MHD simulations and confirm that, in order to have a significant effect on the distribution of matter on large scales, the primordial magnetic field strength would have to be significantly higher than the current observational and theoretical constraints.