A Weak Fermi Gamma-ray Event Associated with a Halo CME and a Type II Radio Burst

TL;DR

This paper analyzes a 2015 gamma-ray event linked to a halo CME and type II radio burst, confirming proton acceleration in the shock as the cause of sustained gamma-ray emission.

Contribution

It establishes a linear relationship between type II burst properties and SGRE duration, confirming shock-accelerated protons as the source.

Findings

SGRE duration correlates with type II burst ending frequency.

Protons accelerated in the shock produce the gamma-ray emission.

The event supports shock acceleration as the origin of sustained gamma rays.

Abstract

We report on the 2015 June 25 sustained gamma-ray emission (SGRE) event associated with a halo coronal mass ejection and a type II radio burst in the decameter-hectometric (DH) wavelengths. The duration and ending frequency of the type II burst are linearly related to the SGRE duration as found in previous works involving intense gamma-ray events. This study confirms that the SGRE event is due to protons accelerated in the shock that produced the DH type II burst.