Galactic cosmic ray propagation models using Picard

TL;DR

This paper introduces PICARD, a new Galactic cosmic-ray transport code capable of detailed, anisotropic diffusion modeling and high-resolution simulations, improving understanding of cosmic-ray spectra and gamma-ray emissions.

Contribution

The paper presents PICARD, a novel numerical code for cosmic-ray transport that incorporates anisotropic diffusion and high-resolution modeling, advancing cosmic-ray astrophysics research.

Findings

PICARD efficiently computes cosmic-ray spectra and gamma-ray emission.

The code models the transition from axisymmetric to spiral-arm source distributions.

Model predictions are compared with observational data.

Abstract

We present results obtained from our newly developed Galactic cosmic-ray transport code PICARD, that solves the cosmic-ray transport equation. This code allows for the computation of cosmic-ray spectra and the resulting gamma-ray emission. Relying on contemporary numerical solvers allows for efficient computation of models with deca-parsec resolution. PICARD can handle locally anisotropic spatial diffusion acknowledging a full diffusion tensor. We used this framework to investigate the transition from axisymmetric to spiral-arm cosmic-ray source distributions. Wherever possible we compare model predictions with constraining observables in cosmic-ray astrophysics.