论文标题

晶状体的进液可以在超音速积聚中产生QPO吗?

Can Lense-Thirring precession produce QPOs in supersonic accretion flows?

论文作者

Marcel, G., Neilsen, J.

论文摘要

X射线二进制文件的时序特性仍然尚不清楚,尤其是其X射线功率谱中的准周期振荡(QPO)。透明裂纹进动的固体体制是一种突出的模型,用于解释最常见的QPO类型。但是,固体体化进度需要一种特定的结构,该结构尚未根据积聚流的约束性质进行检查。我们假设在本文中,正如固体进步所需的那样,一个磁盘在过渡半径$ r_t $的两个流中分为两个流:冷的外流和热的内部流动(扮演电晕的角色)。我们使用积聚参数的模型无关估计来探索两种流的物理结构。我们表明,为了在发光硬状态下重现观测到的X射线光谱,热流必须以声音到超音速的速度吸收,而典型的粘性扭矩无法达到超音速。由于这种极端的积聚速度(或高$α$参数),在这些状态下,磁盘的任何区域都在于固体体化进度所需的“波浪状”状态。此外,我们希望流通过半径$ r _ {\ rm break}> r_t $在半径$ r _ {\ rm break}> r_t $内部的Bardeen-petterson效应与黑洞旋转轴保持一致。结果,在发光硬状态下,热内流无法表现出固体身体进动 - 如目前所示。由于C型QPO在这些状态下很普遍,因此我们得出结论,这种机制不太可能负责在恒星质量黑洞周围产生C型QPO。

The timing properties of X-ray binaries are still not understood, particularly the presence of quasi-periodic oscillations (QPOs) in their X-ray power spectra. The solid-body regime of Lense-Thirring precession is one prominent model invoked to explain the most common type of QPOs, Type C. However, solid-body precession requires a specific structure that has not been examined in light of constrained properties of accretion flows. We assume in this paper, as solid-body precession requires, a disk separated into two flows at a transition radius $r_t$: a cold outer flow and a hot inner flow (playing the role of the corona). We explore the physical structure of both flows using model-independent estimates of accretion parameters. We show that, in order to reproduce the observed X-ray spectra during luminous hard states, the hot flow must accrete at sonic to supersonic speeds, unreachable with typical viscous torques. As a result of this extreme accretion speed (or high $α$ parameter), no region of the disk during these states lies in the `wave-like' regime required for solid-body precession. Furthermore, we expect the flow to align with the black hole spin axis via the Bardeen-Petterson effect inside a radius $r_{\rm break}>r_t$. As a consequence, the hot inner flow cannot exhibit solid body precession -- as currently pictured in the literature -- during luminous hard states. Since Type C QPOs are prevalent in these states, we conclude that this mechanism is unlikely to be responsible for producing Type C QPOs around stellar mass black holes.

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