翘曲吸积盘中的黑洞自旋演化
Black hole spin evolution in warped accretion discs
摘要：
居住在星系核中的大质量黑洞（BH）只能用两个参数来描述，即质量和自旋，它们随着宇宙时间的变化而变化，以响应吸积和合并事件。虽然大多数数值模拟准确地跟踪BH质量，但很少考虑自旋演化。在这项工作中，我们实现并验证了一个自洽的亚网格模型的BH质量和自旋通过气体吸积的流体动力学代码GIZMO的演变。该模型假设，从解决尺度吸积不会瞬间发生，但介导的亚网格几何薄$α$盘。在半解析地验证我们的模型之后，我们在由环核盘组成的理想化环境中测试它，其中气体吸积到吸积盘上始终由GIZMO确定。在没有任何与吸积相关的反馈的情况下，自旋演化密切跟踪在半解析模型中观察到的，并取决于我们实现的自由参数，如初始BH自旋，吸积盘的角动量，以及气体流入循环的半径。在GIZMO中，我们还将我们的模型与同伴论文中提出的双锥流出模型相耦合，其中反馈轴总是与BH自旋对齐。在这最后一种情况下，中央BH的演变显着不同于以前的情况下，因为反馈过程修改的气体动力学和它的流入率从解决尺度。这种相互作用不能用简单的半解析模型来模拟，而应该用完整的N体流体动力学模拟来处理。
英文摘要：
Massive black holes (BHs) inhabiting galactic nuclei can be described by two parameters only, i.e. mass and spin, that change through cosmic time in response to accretion and merger events. While most numerical simulations accurately track the BH mass, spin evolution is rarely taken into account. In this work, we implement and validate a self-consistent sub-grid model for the evolution of the BH mass and spin via gas accretion in the hydrodynamics code GIZMO. The model assumes that accretion from resolved scales does not occur instantaneously, but is mediated by a sub-grid geometrically thin $α$-disc. After validating our model semi-analytically, we test it in an idealized environment consisting of a circumnuclear disc, where gas accretion onto the accretion disc is consistently determined by GIZMO. In the absence of any accretion-related feedback, the spin evolution closely traces that observed in the semi-analytical models and depends on the free parameters of our implementation, such as the initial BH spin, angular momentum of the accretion disc, and the radius at which the gas inflow circularises. In GIZMO, we also couple our model with the biconical-outflow model presented in a companion paper, wherein the feedback axis is always aligned with the BH spin. In this last case, the evolution of the central BH differs significantly from the previous cases, since the feedback process modifies the gas dynamics and its inflow rates from resolved scales. Such an interaction cannot be modeled by simple semi-analytical models and should be treated using full N-body hydrodynamical simulations.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
