Galactic Cosmic Ray Heliosheath Modulation Modeling Tools: a SPECTRUM fork

This is a specialization of the Space Plasma and Energetic Charged particle TRansport on Unstructured Meshes (SPECTRUM) software applied to modeling galactic cosmic rays (GCR) in the heliosphere. Specifically, the codes in this repository simulate GCR modulation in the heliosheath, i.e. the region of space between the supersonic solar wind and the local interstellar medium, analyze the results, and generate useful figures for a future scientific publication. For this application, the model of the heliosphere is analytic with the following main features: the termination shock (TS) and heliopause (HP), which bound the heliosheath, are spherical, the HP is the outer boundary of the simulation domain, i.e. there is no explicit model for the interstellar medium, the solar wind is radially uniform up to the TS, then decreases squared inverse of radial distance, the heliospheric current sheet is warped and advected with the plasma flow with a solar cycle dependent tilt angle, the magnetic field has a Parker spiral configuration which adapts to the radially changing solar wind speed and has a polar correction to the azimuthal component, the temporal behavior of the solar wind is data-informed, i.e. calibrated to be consistent with remote and in-situ (1 au) measurements. The boundary conditions for GCR quantities are obtained from measurements taken by the Voyager spacecrafts, and the diffusion coefficients dictating the particle transport are empirical. The simulations are run along a simulated trajectory of Voyager 2 (V2) within the simplified heliospheric model. IMPORTANT NOTE This is NOT the official SPECTRUM repository, which is archived in Zenodo (DOI: 10.5281/zenodo.10994173). For information about SPECTRUM, visit https://github.com/vflorins/SPECTRUM. This stand-alone specialization of SPECTRUM was made by the original developers for the purpose of ensuring replicability of the results in the associated ApJ publication (DOI: 10.3847/1538-4357/ae5c02). In particular, files that were not relevant in this study (e.g. benchmark/test codes) were removed, and plotting scripts specific to this application were added. In addition, programming macros, simulation constants, and other metaparameters were set to their optimal values for this application. A few application-specific functions/classes may exist that are not present in the general version of SPECTRUM, but any features worth keeping or bug fixes made through this project were back-ported accordingly.