黑洞吸积弥散介质的理论及其应用  

Accretion of Diffuse Medium around Black Holes:the Model and Applications

作　　者：沈璐 刘碧芳[1,2] 乔二林 程华清[1] SHEN Lu;LIU Bi-fang;QIAO Er-lin;CHENG Hua-qing(Key Laboratory of Space Astronomy and Technology,National Astronomical Observatories,Chinese Academy of Sciences,Beijing,100101,China;School of Astronomy and Space Sciences,University of Chinese Academy of Sciences,Beijing,100049,China)

机构地区：[1]中国科学院国家天文台空间天文与技术学重点实验室,北京100101 [2]中国科学院大学,北京100049

出　　处：《天文学进展》2022年第1期37-57,共21页Progress In Astronomy

基　　金：国家自然科学基金(11773037)。

摘　　要：黑洞吸积理论是现代高能天体物理学重要的理论基础,是检验黑洞周围强引力场中物质运动规律的重要理论工具。传统的黑洞吸积模型建立在双星基础上,假设被吸积气体来源于伴星的洛希瓣气体流(RLO),严格意义上适用于小质量X射线双星(LMXB)。对于以天鹅座X-1(Cyg X-1)为代表的大质量X射线双星(HMXB)和中心存在着超大质量黑洞的活动星系核(AGN),吸积气体大多来自于恒星星风、星际介质、尘埃环等弥散介质,因此,吸积流的物理图像与小质量黑洞双星的吸积会有一定程度的差异。综述近年来初步建立的以弥散介质为吸积原料的黑洞吸积模型。详细描述了模型的物理基础、求解过程、由数值计算所得到的吸积流结构、辐射光谱,以及在黑洞双星和活动星系核中的应用,并展望未来理论上的拓展及其应用前景。The black hole accretion theory is an important theoretical basis of modern high-energy astrophysics,as well as an important theoretical tool for testing the law of matter movement in the strong gravitational field around the black hole.The traditional black hole accretion model is suitable for low mass X-ray binaries(LMXB)in a strict sense,which is based on black hole binaries assuming that the accreted gas comes from the Roche lobe overflow(RLO)of the companion star.While for the high mass X-ray binaries(HMXB)represented by Cyg X-1 and the active galactic nuclei(AGNs)with supermassive black holes in the center,most of the accreted gas comes from diffuse media such as stellar wind,interstellar medium and torus,etc.Under such circumstances,the accretion flow at the outer boundary tends to have a much higher temperature,larger velocity dispersion and more stochastic angular momentum distribution than that of the LMXBs,which could create a different scenario of the accretion process.This is the basic assumption,and also,the innovation point of our diffuse media accretion model.In this model,the accretion flow appears as an ADAF-like hot gas when it enters the system.As the accretion flow moves towards the black hole,the increase of the gas density facilitates the Coulomb collisions between ions and electrons thus enhancing the radiation.Specifically,when the initial accretion rate is above a critical value(typically m≈0.02 mEdd),the over-cooling of the corona in the inner region would lead to part of the coronal flow condensing into a cold disk,forming a hybrid two-component accretion flow from ISCO to a certain distance,defined as the condensation radius.Beyond this radius the accretion flow maintains as ADAF.This paper summarizes the recently-established diffuse media accretion model in details,including the physical basis of the model,the solution procedure of the equation set,as well as the numerically calculated structure and emergent spectrum of the accretion flow.Model application to two types of black hol

关 键 词：吸积盘 黑洞物理 活动星系核 X射线双星 

分 类 号：P145.8[天文地球—天体物理]