Measurement of the distribution along the Galactic plane and spectra of low-energy cosmic rays by precise observations of cosmic X-rays

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14491
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Kindai University
• Principal Investigator: Nobukawa Kumiko 近畿大学, 理工学部, 講師 (60815687)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 宇宙線 / 天の川銀河 / 超新星残骸 / X線天文学

Outline of Final Research Achievements

The origin of Galactic cosmic rays is one of the unsolved problems in high-energy astrophysics. Until now, only thermal particles (in the keV band) and high-energy cosmic rays (in the GeV-TeV band) have been observed, while the observational data of the low-energy cosmic rays (in the keV-MeV band) have not been scarce. We devised a "low-energy cosmic-ray measurement using X-ray emission lines from neutral iron" and demonstrated it by observing supernova remnants and the Galactic plane of the Milky Way. In this study, we investigated the distribution and spectra of low-energy cosmic rays in the Galaxy not only through X-ray observations but also through radio observations and theoretical studies.

Free Research Field

X線天文学

Academic Significance and Societal Importance of the Research Achievements

我々の手法である中性鉄からのX線輝線を用いた低エネルギー宇宙線の探査は、シンプルな物理過程を基にしている。「すざく」衛星は鉄輝線バンドで低バックグラウンドかつ高い検出感度とエネルギー分解能をもち、広がった中性鉄からのX線輝線に対して世界最高レベルの性能を持つ。そのため、この視点に注目した研究は他にない。本手法をさらに発展させるため、本研究では2023年度打ち上げのX線天文衛星「XRISM」の較正を行い、低エネルギー宇宙線研究だけでなく、国内外の「XRISM」観測に対しても重要な貢献を果たした。