Comparison of Different Methods for Nonlinear Diffusive Shock Acceleration

TL;DR

This paper compares various numerical, Monte Carlo, and semi-analytical methods for modeling nonlinear diffusive shock acceleration, showing they produce consistent results across different approaches for typical parameters.

Contribution

It provides a comprehensive comparison of different modeling approaches for nonlinear diffusive shock acceleration, highlighting their agreements, differences, and respective strengths and limitations.

Findings

Different methods yield consistent shock hydrodynamics results.

Cosmic ray spectra are similar across approaches.

Escaping flux spectra and anisotropies agree among models.

Abstract

We provide a both qualitative and quantitative comparison among different approaches aimed to solve the problem of non-linear diffusive acceleration of particles at shocks. In particular, we show that state-of-the-art models (numerical, Monte Carlo and semi-analytical), even if based on different physical assumptions and implementations, for typical environmental parameters lead to very consistent results in terms of shock hydrodynamics, cosmic ray spectrum and also escaping flux spectrum and anisotropy. Strong points and limits of each approach are also discussed, as a function of the problem one wants to study.