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2025.07.31
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[College of Science and Engineering] The LST international collaborative research team, including Professor Ryo Yamazaki and Assistant Professor Shuta Tanaka, "Detection of the brightest gamma-ray burst in history with a Cherenkov telescope - New insights into the structure of particle jets"
Research points
◆We have successfully detected high-energy gamma rays from the brightest gamma-ray burst ever observed using the Cherenkov telescope LST-1.
◆This is the only instance of a Cherenkov telescope successfully detecting this gamma-ray burst.
◆The discovery that the flow of accelerated particles, or jets, has a multilayered structure has brought new insights into the generation mechanism of this celestial object and the study of high-energy particle acceleration there.
Summary of Research Findings
The CTAO Observatory's LST international collaborative research team, comprised of members from the University of Tokyo, Chiba University, Kyoto University, and others, and including Professor Ryo Yamazaki and Assistant Professor Shuta Tanaka (both from College of Science and Engineering Department of Physical Sciences) of our university, has successfully detected high-energy gamma-ray radiation from GRB 221009A, the brightest gamma-ray burst (GRB) in observational history (Figure 1).
The observation was conducted in October 2022 using the Cherenkov telescope LST-1 (hereinafter referred to as the LST-1 telescope) located on La Palma Island in the Canary Islands, Spain (Figure 2). This successful detection is the only one achieved using a Cherenkov telescope for observations of GRB 221009A, and only the fifth such detection since the initial detection in 2019, including other GRBs. Analysis of the acquired data revealed that this GRB has a multi-layered jet structure, providing new insights into the GRB generation mechanism and the high-energy particle acceleration that occurs there.
