激波吸积流的混合盘几何：揭示黑洞X射线双星中的准周期振荡
Hybrid disc geometry for shocked accretion flows: Unveiling QPOs in black hole X-ray binaries
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中文总结 AI 辅助
该研究针对黑洞激波吸积流，提出混合盘几何模型，可匹配模拟的流特性，揭示激波振荡是黑洞X射线双星准周期振荡的起源，能重现观测到的准周期中心频率。
中文摘要 AI 辅助
我们研究半解析全局吸积解在捕捉黑洞激波吸积二维数值模拟所观测到的流特性方面的效能。对比分析显示，没有任何单一的盘几何结构能在整个径向域内与模拟剖面充分匹配：激波前区域与锥形盘几何吻合度更高，而激波后区域更适合用垂直平衡盘描述，该区域增强的热压力会导致显著的垂直膨胀。受这种互补行为的启发，我们引入了一种混合盘几何，其中激波前流遵循锥形解，激波后流达到垂直平衡。该混合模型能令人满意地重现激波吸积流的动力学和热力学特性，其预测的马赫数和温度剖面与模拟结果高度吻合，推断的激波位置差异约为10%。在该框架内，我们针对弱旋转和快速旋转黑洞，描绘了由流的能量（$\boldsymbol{\textit{E}}$）和角动量（$\boldsymbol{\textit{\u03bb}}$）构成的激波参数空间，并探究了黑洞X射线双星（BH-XRBs）中准周期振荡（QPOs）的可能起源。我们对能重现观测到的QPO中心频率（$\boldsymbol{\nu_{\rm QPO}}$）的流参数进行了约束，证明激波前的振荡为低频和高频QPO提供了自洽机制。将分析扩展至10个银河系BH-XRBs，我们表明观测到的$\boldsymbol{\nu_{\rm QPO}}$可在物理上合理的参数范围内被重现，这确立了激波全局吸积解作为解释吸积驱动时间变异性的潜在极具吸引力的框架。
英文摘要
We investigate the efficacy of semi-analytical global accretion solutions in capturing the flow properties observed in two-dimensional numerical simulations of shocked accretion onto black holes. A comparative analysis reveals that no single disc geometry adequately matches the simulation profiles across the entire radial domain. The pre-shock region exhibits closer agreement with the conical disc geometry, while the post-shock region is better described by the vertical equilibrium disc, where enhanced thermal pressure leads to substantial vertical expansion. Motivated by these complementary behaviours, we introduce a hybrid disc geometry in which the pre-shock flow follows the conical solution and the post-shock flow attains vertical equilibrium. This hybrid model satisfactorily reproduces both dynamical and thermodynamical properties of shocked accretion flows with the predicted Mach number and temperature profiles closely matching the simulations and the inferred shock location differing by $\sim10\%$. Within this framework, we delineate the shock parameter space spanned by the energy ($\mathcal{E}$) and angular momentum ($λ$) of the flow for weakly and rapidly rotating black holes and investigate the possible origin of Quasi-periodic Oscillations (QPOs) in black hole X-ray binaries (BH-XRBs). We constrain flow parameters that reproduce observed QPO centroid frequencies ($ν_{\rm QPO}$) demonstrating that oscillations of the shock front provide a self-consistent mechanism for both low and high frequency QPOs. Extending the analysis to ten Galactic BH-XRBs, we demonstrate that the observed $ν_{\rm QPO}$ are reproduced within physically plausible parameter ranges, which establishes shocked global accretion solutions as a potentially compelling framework for interpreting accretion driven temporal variability.
