大质量黑洞潮汐瓦解恒星事件中的动力学和辐射性质

The stellar tidal disruption events (TDEs) by massive black holes provide new channels for studying the super-Eddington accretion physics, the demography and growth of massive black holes, and to test the general relativity. The development of time-domain astronomy in the last five years has increased the TDE sample rapidly, but also brought three major challenges to the classical TDE theory. First, those hard X-ray selected TDEs show abrupt declines in their late time flux. Second, some TDEs show non-thermal radio afterglows which are not predicted by the classical theory. Third, the newest TDE was found to have occurred in a possibly low luminosity active galactic nucleus. To address these challenges, we will apply a model about accretion disk state transition to those hard X-ray selected TDEs and explain their abrupt flux drop-off. We will also calculate the shock interaction between the star's unbound tidal debris and the ambient medium, and its synchrotron radiation as an origin for the radio afterglow. Lastly, we will study the interaction between the pre-disruption star and/or the post-disruption debris with a pre-exisiting accretion disk. The research proposed here will improve our understanding of the physics of super-Eddington accretion, the dynamics of TDE and the associated multi-wavelength signal, and will guild an observational hunt for TDEs happening in active galaxies.

大质量黑洞潮汐瓦解恒星事件（Tidal Disruption Events，简称TDE）是研究超爱丁顿暂现吸积物理、统计宇宙中大质量黑洞数目及增长、检验广义相对论的新兴渠道。近五年暂现源巡天的发展不仅使TDE观测样本快速增长，也带给TDE经典理论模型三个挑战：主要辐射能量在硬X射线的TDE在晚期光度有奇怪的急剧陡降；一部分TDE有经典理论没有预测的非热射电辐射；最新的一个TDE的宿主星系可能是一个低光度活动星系核。为解决这些挑战，本项目将（1）应用暂现吸积盘态转换模型至硬X射线TDE样本，以解释晚期光度急剧变暗；（2）计算恒星瓦解后逃逸的残骸与周围介质的激波作用，以解释TDE的射电辐射；（3）研究恒星在瓦解前，以及瓦解后的回落残骸，与黑洞周围预先存在的吸积盘之间的相互作用。本项目预计会推进对黑洞超爱丁顿吸积物理、TDE多波段观测信号的理解，并指导观测如何寻找活动星系中的TDE。

本项目研究大质量黑洞潮汐瓦解恒星事件(Tidal Disruption Events，简称TDE)中的动力学和辐射特征。我们详细计算了中等质量黑洞潮汐瓦解主序星事件的一系列动力学过程，包括残骸质量回落率曲线，回落残骸流的圆化产能、形成盘，及其后期的盘吸积过程。在此基础上，我们计算了这类事件的热光度光变曲线及辐射温度演化曲线。我们发现这些预测结果与最近观测到的一个中等质量黑洞TDE候选体的观测特征大致吻合。中等质量黑洞TDE是发现宇宙中可能存在的中等质量黑洞群体的一种新途径。我们的模型预测结果对在观测上搜寻和确认这种事例有重要参考和指导意义。我们提出了中等质量黑洞潮汐剥离白矮星模型用于解释若干例观测到的新型快速超亮X射线暴事件。我们预测了恒星级黑洞与中子星的并合事件中的千新星的偏振观测特征。我们提出并研究了部分内核塌缩型超新星的黑洞回落吸积模型。