Exploration of the origin of Galactic cosmic-rays

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K03647
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Tokyo Metropolitan University (2020-2021); Osaka University (2018-2019)
• Principal Investigator: Fujita Yutaka 東京都立大学, 理学研究科, 教授 (10332165)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 銀河団 / 宇宙線 / 乱流 / 活動銀河核 / 超新星残骸

Outline of Final Research Achievements

Clusters of galaxies are the largest objects in the Universe. They are also the largest accelerators in the universe, containing a large number of cosmic ray particles. We pursued the origin of these cosmic rays. We found that (1) the structure of the cluster of galaxies has specific scaling relations. Turbulence may develop in them based on these relations, and cosmic rays may be accelerated by the turbulence. (2) The supermassive black holes in the center of the clusters also accelerate cosmic rays, and they heat the cluster. (3) The supernova remnants in the Galaxy can be seen as a role model of the acceleration of cosmic rays in the cluster of galaxies.

Free Research Field

宇宙物理学

Academic Significance and Societal Importance of the Research Achievements

銀河団の構造が持つ規則性に銀河団の形成と進化に関わる要素が含まれていることが明らかになった。従って銀河団の中の宇宙線加速もこの規則性に従って理解できることになる。一方、銀河団中心の超巨大ブラックホールも宇宙線を加速しているが、その宇宙線が広がりながら安定に銀河団を加熱していることもわかった。銀河団は地球からは遠く、詳細な観測は難しいが、地球の近傍にある超新星残骸は銀河団での宇宙線加速を知るための代替天体になることも示した。