The Cosmological Simulation Code OpenGadget3 - Implementation of Self-Interacting Dark Matter

TL;DR

This paper introduces the implementation of self-interacting dark matter (SIDM) physics into the OpenGadget3 simulation code, enabling detailed cosmological studies of SIDM effects on structure formation.

Contribution

The paper presents a new, publicly available implementation of SIDM in OpenGadget3, capable of simulating various cross-sections and multi-species interactions, with validation and performance analysis.

Findings

Accurate simulation of DM self-interactions demonstrated

Code supports anisotropic and multi-species SIDM models

Performance and scaling tested successfully

Abstract

Dark matter (DM) could be subject to non-gravitational self-interactions which is relevant to resolve potential problems of cold DM on small scales. Their impact on astrophysical objects such as galaxies and galaxy clusters allows for constraining the strength of this scattering and eventually further properties of the cross-section. To model self-interacting dark matter (SIDM), N-body simulations are a crucial tool widely employed by the SIDM community. In this paper, we describe the SIDM implementation in the cosmological hydrodynamical N-body code OpenGadget3 and release it to the public. It is capable of simulating elastic scattering for various differential cross-sections, including strongly anisotropic cross-sections. Beyond single-species models, the code also allows simulating a two-species model with cross-species interactions. In addition to describing the numerical schemes for modelling various flavours of SIDM, we discuss the technical challenges of implementing them. Moreover, we demonstrate through several test problems that OpenGadget3 can accurately simulate DM self-interactions. Furthermore, we assess the performance of the code and provide scaling tests. Lastly, we highlight remaining challenges in the context of SIDM and describe directions for improving the current state of the art.