致密天体在活动星系核吸积盘中的迁移  

Migration of compact objects in active galactic nucleus accretion disks

作　　者：彭朋 陈弦[1,2] Peng Peng;Xian Chen(Department of Astronomy,School of Physics,Peking University,Beijing 100871,China;Kavli Institute of Astronomy and Astrophysics,Peking University,Beijing 100871,China)

机构地区：[1]北京大学物理学院天文学系,北京100871 [2]北京大学科维理天文与天体物理研究所,北京100871

出　　处：《科学通报》2025年第3期363-372,共10页Chinese Science Bulletin

基　　金：国家自然科学基金(11991053)资助。

摘　　要：对活动星系核吸积盘中恒星级致密天体的研究,始于20世纪人们对类星体光谱中金属发射线的观测和理论研究工作.近年来,由于引力波观测取得的长足进展,尤其是地面引力波探测器发现了一批大质量的恒星级双黑洞,相关的理论研究更加受到人们的重视.这些研究工作发现,星体在活动星系核吸积盘中的迁移过程对理解大质量致密天体的形成和演化具有重要作用.为了梳理这个领域的观测和理论进展,并且总结未来可能的发展方向,本文回顾了致密天体在活动星系核吸积盘中迁移的主要机制,其中包括与吸积盘撞击导致的星体角动量损失、潮汐力矩激发的密度波对星体的反作用、气体非开普勒运动导致的星体吸积和动力学摩擦效应,以及最近提出的一些新机制,如热力矩以及第三体的引力影响等.此外,本文还总结了与致密天体迁移过程相关的天文学观测现象,比如类星体金属增丰,以及恒星级双致密天体或者极端质量比旋近产生的引力波等.最后,本文总结了该领域仍然存在的一些重要理论问题以及值得进一步研究的方向.The interest of studying the formation and evolution of compact objects in the accretion disks of active galactic nuclei(AGNs)dates back to the 21st century.The observational evidence of early metal enrichment in AGNs as well as the variability of AGNs motivated people then to theoretically investigates the formation and motion of compact objects in the accretion disks.More recently,the rapid progress in the observation of gravitational waves(GWs)revived the interest in the above studies.In particular,the high masses of the binary black holes(BHs)discovered by the Laser Interferometer Gravitational-wave Observatory(LIGO)and the Virgo detectors challenge the current standard model of binary BH(BBH)formation,and hence require new insights in the origin of these binaries.The accretion disk of AGNs is a favorable location for such heavy binaries to form because of the possibility of gas accretion and pairing with other BHs.Previous theoretical work on the formation and evolution of stellar-mass objects(e.g.,stars,stellar-mass BHs,etc.)in AGN disks found that migration is one of the most important ingredients in the model that determines the characters of the LIGO/Virgo BBHs.Here,migration stands for the gradual change of the orbital radius of the small object due to its interaction with the surrounding gas or other stellar objects.In this review,we summarize the theoretical and observational progress related to the migration of compact objects in the accretion disks of AGNs,and point to the important problems which need to be addressed in the future.We firstly review three major types of migration which have been investigated in the literature.(1)For the compact objects whose orbits are inclined and not embedded in the disk,every time they hit the accretion disk,the orbital angular momenta are lost due to the collision.(2)Compact objects can excite density waves in the disk,which can transport angular momenta away from the compact objects via the backreaction on the objects.(3)In the case where the orbital velocity o

关 键 词：引力波 致密天体 活动星系核 吸积盘 流体力学 

分 类 号：P157.6[天文地球—天文学]