Observation of transient objects with the Cherenkov Telescope Array telescopes

2019 Fiscal Year Final Research Report

• Project/Area Number: 19K21043
• Project/Area Number (Other): 18H05858 (2018)
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund (2019); Single-year Grants (2018)
• Review Section: 0203:Particle-, nuclear-, astro-physics, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Noda Koji 東京大学, 宇宙線研究所, 准教授 (00816837)
• Project Period (FY): 2018-08-24 – 2020-03-31
• Keywords: 高エネルギーガンマ線 / 突発天体 / ガンマ線バースト / チェレンコフ望遠鏡 / 電源システム

Outline of Final Research Achievements

We aim to observe and understand transient objects in the Universe, such as gamma-ray bursts, using telescopes in an international collaborative project, Cherenkov Telescope Array. CTA Large Size Telescope (LST) requires a special high-power supply system in order to point to any object in the sky and start to observe it within 20 seconds. In this program we first developed and deployed a monitoring and alerting systems of the power supply system, and achieved a stable operation, leading to obtaining gamma-ray signals from Crab Nebula as expected. In parallel, using MAGIC telescopes, which are the model of LSTs and are located at the same observational site as LST, we finally discovered gamma rays with energies beyond teraelectronvolt from a gamma-ray burst, and have obtained an insight into its gamma-ray emission mechanism.

Free Research Field

高エネルギーガンマ線天文学

Academic Significance and Societal Importance of the Research Achievements

ガンマ線バーストの素性は長らく謎に包まれていたが、今世紀に入り研究が活発化し、メガ電子ボルトのガンマ線やエックス線、さらに長い（エネルギーの低い）波長領域での理解が進んだ。しかしギガ電子ボルト以上のガンマ線放射については、放射機構は謎のままであり、テラ電子ボルトに至っては未発見であった。本研究はこれを突破する初の発見となり、そのインパクトは非常に大きい。本成果はMAGIC望遠鏡によってなされたが、CTA LSTは言わばMAGICのアップグレード版であり、MAGICでの発見が今後LSTに引き継がれ強力に進むことは疑いがない。その意味でLSTを安定運用につなげた本研究の成果も同様に重要である。