宇宙射線在星際物質與物質流中之傳輸及動力影響( I );Propagation and Dynamical Influence of Cosmic Rays on Interstellar Medium and Outflow( I )

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题名:	宇宙射線在星際物質與物質流中之傳輸及動力影響( I );Propagation and Dynamical Influence of Cosmic Rays on Interstellar Medium and Outflow( I )
作者:	高仲明
贡献者:	國立中央大學天文研究所
关键词:	宇宙射線;高能粒子傳輸;粒子加速;磁流波;分子雲;星系風;費米泡;cosmic rays;energetic particle propagation;particle acceleration;hydromagnetic waves;molecular clouds;galactic wind;Fermi bubbles
日期:	2020-01-13
上传时间:	2020-01-13 14:05:41 (UTC+8)
出版者:	科技部
摘要:	除了星際氣體及電漿外，宇宙射線與磁場是星際介質生態系統的重要品種。我們對宇宙射線與電漿的交互作用很感興趣。在這個計畫我們將專注在（一）宇宙射線傳輸與加速，（二）宇宙射線之動力學效應。經過多年研究，宇宙射線傳輸有個「標準模型」。不過我們覺得它在某些環境下有些不足，如在分子雲或星系風中。我們將嘗試從新從第一原理出發做些關鍵修改以彌補不足。我們最關心的是決定不同傳輸行為的物理，如「彈道式」和「擴散式」。我們預期會推導出一組新的宇宙射線傳輸與波串級方程組。在分子雲和星系風的模型裡仔細研究這方程組，將提供我們道路如何理解宇宙射線與它們的源在銀河的分布為何不一樣的。近來科學家開始意識到宇宙射線對星際物質回饋的重要性。熱氣、輻射和宇宙射線被認為是恆星形成活動的三個最重要因素。我們將從動力學回饋這個角度去探討宇宙射線的影響。我們在宇宙射線之流體描述有豐富經驗。我們建立含熱氣或電漿、宇宙射線及磁流波的多流體模型。我們將尋找可能的雲的靜態結構與風的穩態分布。從這些結構與分布，我們可辨認出宇宙射線影響恆星形成活動的關鍵物理。最近對費米泡（在銀心兩個巨大結構）的數值模擬顯示在費米泡側面有大尺度的剪流。這驅使我們重新認真的再研究鮮為人知的一種宇宙射線加速機制稱作「宇宙射線粘性」。我們也打算推導含這個加速機制的流體模型。 ;In addition to interstellar gas and plasma, cosmic rays and magnetic field are important species in the ecology of interstellar medium. We are interested in the interaction between cosmic rays and plasma. In this proposal we concentrate on (1) cosmic ray propagation and acceleration, and (2) dynamical effects of cosmic rays.After years of study, a “standard model” of cosmic ray propagation has emerged. However, we deem that there are some deficiencies of the “standard model” in certain environments or situations, such as molecular cloud and galactic wind. We would like to start anew from first principle to make key revision to overcome the deficiencies. In particular, we are concerned about the physics defining different transport regimes, namely, the “ballistic” and “diffusive” regimes. We anticipate to derive a new set of cosmic transport and wave-cascade equations. A detail study of this set on molecular cloud and possible galactic wind model will provide us a path to understand the mismatch between the distribution of cosmic rays and their sources in our Galaxy.Recently, scientists become aware of the importance of cosmic ray feedback on interstellar matter. Thermal gas, radiation and cosmic rays are regarded as the three most important factors in star formation activity. We want to investigate the influence of cosmic rays from the angle of dynamical feedback. We have plenty of experience in hydrodynamic description of cosmic ray. We can set up multi-fluid models that comprise thermal gas or plasma, cosmic rays and hydromagnetic waves. We will seek possible hydrostatic cloud structures, and steady state wind profiles. From these structures and profiles, we can identify the crucial physics of the influence of cosmic rays on star formation activity.Recent numerical simulation on Fermi bubbles (two giant structure at the Galactic centre) showed the existence of a large scale shear flow at the lateral side of the bubbles. This persuades us to study seriously the rarely mentioned cosmic ray acceleration mechanism called “cosmic ray viscosity”. We also would like to derive the fluid model including this acceleration mechanism.
關聯:	財團法人國家實驗研究院科技政策研究與資訊中心
显示于类别:	[天文研究所] 研究計畫

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