报告题目：The Cosmic Ray-Dominated Circumgalactic Medium

　　报告人：季索清（加州理工学院Walter Burke理论物理研究所Sherman Fairchild Fellow）

　　报告人简介：2018年于加州大学圣塔芭芭拉分校获得物理学博士学位，现为加州理工学院Walter Burke理论物理研究所Sherman Fairchild Fellow。主要研究方向为星系团、星系形成。较早地开展了关于微观物理过程和非热过程对环星系介质（circumgalactic medium）的影响的系统研究，包括湍流、流体及热不稳定性、磁场和宇宙射线。担任NASA Astrophysics Theory Program、NSF Astronomy项目评审人。

　　报告摘要：Recent observations suggest that large quantities of cool gas are found in the circumgalactic medium (CGM) of the galaxy halo, with temperatures of a few 10^4 K. In addition, detections of highly-ionized oxygen (O VI) indicate the existence of warm gas at a few 10^5 K around star-forming galaxies. However, the origin and stability of the combined cool, warm and hot multiphase CGM are not fully understood yet. With the FIRE-2 simulations in which cosmic ray physics is incorporated, we have found that Milky Way-mass galaxy halos at low redshifts could potentially be dominated by cosmic ray pressure rather than ordinary thermal gas pressure. This insight fundamentally reshapes our understanding of the physical states of the multiphase CGM, and may help solve long-standing puzzles such as the survival of the ubiquitous cool gas, and the usually under-predicted O VI.

　　报告时间：2019年12月20日（星期五）上午10:30

　　报告地点：紫台仙林3-302会议室

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紫金山天文台学术委员会