Systematic Study of the Simultaneous Events Detected by GECAM

TL;DR

This study analyzes simultaneous high-energy events detected by GECAM, revealing they likely originate from cosmic ray interactions, and demonstrates GECAM's capability as a micro cosmic-ray observatory.

Contribution

First comprehensive analysis of simultaneous events in GECAM data, identifying their properties and origin, and establishing GECAM as a tool for cosmic-ray detection.

Findings

STE likely caused by cosmic ray interactions

GECAM can detect and characterize high-energy cosmic rays

GECAM functions as a micro cosmic-ray observatory

Abstract

GECAM is a constellation of all-sky monitors in hard X-ray and gamma-ray band primarily aimed at high energy transients such as gamma-ray bursts, soft gamma-ray repeaters, solar flares and terrestrial gamma-ray flashes. As GECAM has the highest temporal resolution (0.1~$\mu$s) among instruments of its kind, it can identify the so-called simultaneous events (STE) that deposit signals in multiple detectors nearly at the same time (with a 0.3~$\mu$s window). However, the properties and origin of STE have not yet been explored. In this work, we implemented, for the first time, a comprehensive analysis of the STE detected by GECAM, including their morphology, energy deposition, and the dependence on the geomagnetic coordinates. We find that these STE probably result from direct interactions between high-energy charged cosmic rays and satellite. These results demonstrate that GECAM can detect, identify, and characterize high-energy cosmic rays, making it a Micro Cosmic-Ray Observatory (MICRO) in low Earth orbit.