# Combined Magnetohydrodynamic- Monte Carlo Simulations of Proton Acceleration in Colliding Wind Binaries

## TL;DR

This paper combines magnetohydrodynamic and Monte Carlo simulations to study proton acceleration in colliding-wind binary systems, aiming to improve gamma-ray flux predictions by modeling shock acceleration processes.

## Contribution

It introduces a self-consistent approach integrating MHD and Monte Carlo simulations to analyze proton acceleration at both shocks in CWBs, considering magnetic field effects.

## Key findings

- Protons are efficiently accelerated at both shocks in CWBs.
- Magnetic field topology significantly influences particle acceleration.
- Results can refine gamma-ray emission predictions for CWBs.

## Abstract

The interaction between the strong winds of the stars in colliding-wind binary (CWB) systems produces two shock fronts, delimiting the wind collision region (WCR). There, particles are expected to be accelerated mainly via diffusive shock acceleration, and to produce $\gamma$-rays, in processes involving relativistic electrons and/or protons. We investigate the injection and the acceleration of protons in typical CWB systems by means of Monte Carlo simulations, with a test-particle approach. We use magnetohydrodynamic simulations to determine the background conditions in the wind collision region. This allows us to consider particle acceleration at both shocks, on either side of the WCR, with a self-consistently determined large-scale magnetic field, which has an impact on the shape of the WCR, and the topology of which plays an important role in particle acceleration at collisionless shocks. Such studies may contribute to improve $\gamma$-ray flux predictions for CWB systems.