致密天体辐射特征与物理性质

Physical and radiation properties of compact objects

致密天体作为恒星演化的最终产物,是探索极强引力、高密度、强磁场物理环境的宇宙实验室.受限于观测手段和致密天体独特的性质,截至目前,只有极少部分致密天体被发现,因此其物理性质和演化依然成谜.致密天体的观测和研究需要借助它与其他天体的相互作用来进行.基于武汉大学近几年的研究成果,本文从X射线双星、球状星团、超大质量黑洞3个方面对中子星和黑洞研究进行了总结.首先,对双星中黑洞和中子星的吸积特征进行了介绍,重点是回旋吸收线方面的研究.然后,介绍了小波分析方法在双星领域的首次应用.该方法所提供的更加精确的时频域信息能够对准周期振荡信号进行更加详细的分析.另外,致密天体与球状星团也有着密不可分的关系.致密的星团环境一方面为黑洞捕获其他天体形成X射线双星、引力波源乃至中等质量黑洞等天体提供了绝佳的场所,另一方面也为研究黑洞在球状星团中的动力学演化过程带来许多观测可能.最后,通过展示潮汐撕裂恒星事件和银心附近气泡等现象的相关研究成果,对超大质量黑洞的性质和特征进行了分析,为了解其吸积过程、活动机制、周边云团环境等提供了帮助.

As the final product of stellar evolution,compact objects serve as cosmic laboratories for exploring extremely strong gravitational,high-density,and strong magnetic field environments.However,due to the limitations of observation methods and the unique properties of compact objects,only a very small part has been discovered to date,thus their physical properties and evolution remain a mystery.The observation and study of compact objects often require their interaction with other celestial bodies.Therefore,based on recent research results from Wuhan University,this review summarizes the related research on neutron stars and black holes through three aspects:X-ray binaries,globular clusters,and supermassive black holes.This review first introduces the accretion features of black holes and neutron stars in binary systems.Due to the strong magnetic field in neutron stars,the accretion features and radiation environment of a neutron star binary system are more complex compared to those of a black hole binary system.The center energy of the cyclotron absorption line is a key factor in determining the strength of the magnetic field of a source.Thus,thanks to the wide energy range and unique advantages of the Insight-HXMT satellite,this review focuses on the study of cyclotron absorption lines to limit the magnetic field and accretion model of the neutron star.Additionally,this review introduces the first application of wavelet analysis in the field of binary systems.The more accurate time-frequency domain information obtained by this method can provide much more detailed information of the quasi-periodic oscillation signals,offering features that cannot be obtained by traditional power density spectra and contributing to a deeper understanding of the mechanism of quasiperiodic oscillations.Furthermore,there is an inseparable relationship between compact objects and globular clusters.The compact cluster environment provides an excellent location for black holes to capture other celestial bodies and form X-ray binary systems,gravitational wave sources,and even intermediate-mass black holes.On the other hand,the dynamic process of black holes can change the dynamic structure and evolutionary process of host clusters,as well as the evolution,distribution,and abundance of visible binary systems in the clusters.This,in turn,provides many observational possibilities for studying the dynamic evolution process of black holes in globular clusters.Finally,supermassive black holes are generally located in the center of large galaxies,such as Sagittarius A* at the center of the Milky Way,and have unique physical properties and observational features,such as the evolution of active galactic nuclei,tidal disruption events,and bubble structures near the galactic center.Unlike the much longer evolution timescales of active galactic nuclei,the physical processes involved in tidal disruption events,such as the formation of accretion disks,the state transition from high to low accretion rates,and the generation of outflows,are condensed within just a few months to a few years.This provides an important sample for relevant research.Moreover,bubbles near the galactic center are often considered to be related to the activity history of the galactic center.By displaying research results on tidal disruption events and bubbles near the galactic center,this review analyzes the properties and features of supermassive black holes,providing insights into their accretion processes,activity mechanisms,and surrounding cloud environments.