Cosmic-ray propagation with DRAGON2: I. numerical solver and astrophysical ingredients

TL;DR

DRAGON2 is an advanced numerical tool for modeling cosmic-ray propagation in the galaxy, incorporating realistic astrophysical conditions and allowing flexible, modular simulations to match recent cosmic-ray measurements.

Contribution

This paper introduces DRAGON2, a new version with an improved solver and versatile astrophysical models, enabling more accurate and diverse cosmic-ray transport simulations.

Findings

Enhanced numerical accuracy validated against analytical solutions.

Ability to simulate complex, inhomogeneous cosmic-ray transport scenarios.

Facilitates inclusion of custom physical models through modular design.

Abstract

We present version 2 of the DRAGON code designed for computing realistic predictions of the CR densities in the Galaxy. The code numerically solves the interstellar CR transport equation (including inhomogeneous and anisotropic diffusion, either in space and momentum, advective transport and energy losses), under realistic conditions. The new version includes an updated numerical solver and several models for the astrophysical ingredients involved in the transport equation. Improvements in the accuracy of the numerical solution are proved against analytical solutions and in reference diffusion scenarios. The novel features implemented in the code allow to simulate the diverse scenarios proposed to reproduce the most recent measurements of local and diffuse CR fluxes, going beyond the limitations of the homogeneous galactic transport paradigm. To this end, several applications using DRAGON2 are presented as well. The new version facilitates the users to include their own physical models by means of a modular C++ structure.