The Arepo public code release

TL;DR

The Arepo code is a publicly available, highly efficient cosmological magnetohydrodynamical simulation tool that combines advanced algorithms for gravity, magnetohydrodynamics, and galaxy formation modeling, optimized for parallel computing.

Contribution

This paper introduces the first public release of Arepo, a versatile, parallel, moving-mesh simulation code for cosmological magnetohydrodynamics with integrated sub-grid physics and extensive testing capabilities.

Findings

Efficient high dynamic range simulations achieved.

Deterministic parallelization produces consistent results.

Includes sub-resolution models for galaxy formation.

Abstract

We introduce the public version of the cosmological magnetohydrodynamical moving-mesh simulation code Arepo. This version contains a finite-volume magnetohydrodynamics algorithm on an unstructured, dynamic Voronoi tessellation coupled to a tree-particle-mesh algorithm for the Poisson equation either on a Newtonian or cosmologically expanding spacetime. Time-integration is performed adopting local timestep constraints for each cell individually, solving the fluxes only across active interfaces, and calculating gravitational forces only between active particles, using an operator-splitting approach. This allows simulations with high dynamic range to be performed efficiently. Arepo is a massively distributed-memory parallel code, using the Message Passing Interface (MPI) communication standard and employing a dynamical work-load and memory balancing scheme to allow optimal use of multi-node parallel computers. The employed parallelization algorithms of Arepo are deterministic and produce binary-identical results when re-run on the same machine and with the same number of MPI ranks. A simple primordial cooling and star formation model is included as an example of sub-resolution models commonly used in simulations of galaxy formation. Arepo also contains a suite of computationally inexpensive test problems, ranging from idealized tests for automated code verification to scaled-down versions of cosmological galaxy formation simulations, and is extensively documented in order to assist adoption of the code by new scientific users.