First Detection of the Powerful Gamma Ray Burst GRB221009A by the THEMIS ESA and SST particle detectors on October 9, 2022

TL;DR

This study reports the first detection of the exceptionally bright gamma-ray burst GRB 221009A by the THEMIS spacecraft's particle detectors, revealing detailed temporal structures and complementing gamma-ray telescope observations.

Contribution

It is the first to record and analyze the effects of GRB 221009A using particle detectors aboard the THEMIS mission, providing high-resolution insights into its fine structure.

Findings

Captured the fine temporal structure of GRB 221009A

Resolved the burst's spiky main structure

Complemented gamma-ray telescope data

Abstract

We present the first results study of the effects of the powerful Gamma Ray Burst GRB 221009A that occurred on October 9, 2022, and was serendipitously recorded by electron and proton detectors aboard the four spacecraft of the NASA THEMIS mission. Long-duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars, and, among them, GRB 221009A is so far the brightest burst ever observed due to its enormous energy ($E_{\gamma iso}\sim10^{55}$ erg) and proximity (the redshift is $z\sim 0.1505$). The THEMIS mission launched in 2008 was designed to study the plasma processes in the Earth's magnetosphere and the solar wind. The particle flux measurements from the two inner magnetosphere THEMIS probes THA and THE and ARTEMIS spacecraft THB and THC orbiting the Moon captured the dynamics of GRB 221009A with a high-time resolution of more than 20 measurements per second. This allowed us to resolve the fine structure of the gamma-ray burst and determine the temporal scales of the two main bursts spiky structure complementing the results from gamma-ray space telescopes and detectors.