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碩博班專題討論(Colloquium)

Exploring the thermodynamic properties of the intracluster medium in cool cores of galaxy clusters

演講者 : Shutaro Ueda 上田周太朗 Research Scholar (Academia Sinica Institute of Astronomy and Astrophysics)
演講時間 : 2022 / 09 / 16 14:10
理學教學新大樓物理系1F 36102教室
理學教學新大樓物理系1F 36102教室 位於....
Galaxy clusters are known as the largest gravitationally bound objects in the Universe. X-ray observations discovered a large amount of diffuse, hot X-ray emitting gas with temperature of 10^7-8 Kelvin (so-called intracluster medium; ICM) trapped in deep gravitational potential well dominated by dark matter for the first time. Since the total mass of the ICM is estimated as ~ 10^14 solar mass that is a factor of ~5 larger than the integrated total mass of galaxies in a galaxy cluster, the ICM plays a central role in the evolution of baryons in galaxy clusters. Cool cores are often located at the center of galaxy clusters. They are in the form of the dense, relatively cool, metal enriched ICM. The presence of cool cores poses a challenge for our understanding of the thermal evolution of the baryons. SInce the ICM is losing their thermal energy by X-ray radiation, it was expected that runaway cooling takes place and a massive starburst is induced by a cooled ICM. However, X-ray observations indicate that there is no evidence of such runaway cooling. In this talk, I will introduce this challenge recognized as a long-standing problem in cluster astrophysics and our recent study that is possible to explain this problem. In addition, I will introduce a new generation X-ray observatory XRISM that will open a new window to X-ray astronomy.