Particles Acceleration in Converged Two Shocks

TL;DR

This paper uses Monte Carlo simulations to explore proton acceleration in converged two shocks, revealing a spectral break at around 5MeV, which helps understand observed features in CME-driven shock events.

Contribution

It introduces a novel Monte Carlo simulation approach to model proton spectra in converged shocks, capturing the spectral break phenomenon observed in space weather events.

Findings

Proton energies can reach up to 10MeV in converged shock interactions.

A spectral break at approximately 5MeV naturally emerges in the simulation.

The model supports the diffusive shock acceleration theory for CME shocks.

Abstract

Observations show that there is a proton spectral "break" with E$_{break}$ at 1-10MeV in some large CME-driven shocks. Theoretical model usually attribute this phenomenon to a diffusive shock acceleration. However, the underlying physics of the shock acceleration still remains uncertain. Although previous numerical models can hardly predict this "break" due to either high computational expense or shortcomings of current models, the present paper focuses on simulating this energy spectrum in converged two shocks by Monte Carlo numerical method. Considering the Dec 13 2006 CME-driven shock interaction with an Earth bow shock, we examine whether the energy spectral "break" could occur on an interaction between two shocks. As result, we indeed obtain the maximum proton energy up to 10MeV, which is the premise to investigate the existence of the energy spectral "break". Unexpectedly, we further find a proton spectral "break" appears distinctly at the energy $\sim$5MeV.