[论文解读] Correlated X-ray Spectral and Timing Behavior of the Black Hole Candidate XTE J1550-564

J. Homan, R. Wijnands+6 more|arXiv (Cornell University)|Jan 10, 2000

Astrophysical Phenomena and Observations被引用 4

一句话总结

本文分析了XTE J1550-564的RXTE数据，揭示了黑洞行为的二维状态空间，其中光谱和时域特性（尤其是QPO）与颜色-颜色图中类似梳子的结构相关联。软态构成梳子的中轴，硬态构成梳齿，QPO频率与光谱硬度共同变化，表明吸积速率和康普顿化区域大小是独立的控制参数。

ABSTRACT

We present an analysis of data of the black hole X-ray transient XTE J1550-564, taken with RXTE between 1998 Nov 22 and 1999 May 20. The source went through several different states, which were divided into soft and hard states, based on the relative strength of the high energy power law tail. The states showed up as distinct branches in the color-color diagram, connecting to form a structure with a comb-like topology, the branch corresponding to the soft state forming the spine and the branches corresponding to the various hard states forming the teeth of the comb. The power spectral properties of each branch were correlated with their spectral properties. Three types of QPOs were found: 1-18 Hz and 100-285 Hz QPOs on the hard branches, and 15-18 Hz QPOs on and near the soft branch. The frequency of the high and low frequency QPOs on the hard branches were correlated with each other, and with spectral hardness. The behavior of the XTE J1550-564 strongly favors a two-dimensional description of black hole behavior, where the canonical soft high state is identified with regions near the spine of the comb in the color-color diagram and the canonical very high, intermediate, and low states with its teeth. The difference between the various hard states is associated with the flux of the blackbody component. The two parameters underlying this two-dimensional behavior, vary to a large extent independently, and could for example be the accretion rate through the disk and the size of the Comptonizing region causing the hard tail. We discuss how this picture could tie in with the canonical, one-dimensional behavior of black hole candidates that has usually been observed.

研究动机与目标

• 研究黑洞候选体XTE J1550-564中光谱与时域行为的相关性。
• 利用颜色-颜色图识别源演化中的不同状态。
• 确定准周期振荡（QPO）在不同状态中与光谱硬度和通量的关系。
• 通过提出一个二维框架，挑战传统的单维状态演化模型。

提出的方法

• 分析了1998年11月至1999年5月期间收集的RXTE数据。
• 根据高能幂律尾部的相对强度，将源状态分类为软态和硬态。
• 将状态映射到颜色-颜色图上，揭示出具有软态中轴和硬态梳齿的梳状拓扑结构。
• 识别并表征了三种类型的QPO：硬分支上的1–18 Hz和100–285 Hz QPO，以及软分支上的15–18 Hz QPO。
• 研究了QPO频率、光谱硬度以及黑体组分通量之间的相关性。
• 提出一个二维模型，其中吸积速率和康普顿化区域大小独立控制状态转换。

实验结果

研究问题

• RQ1 XTE J1550-564的不同状态中，QPO频率如何与光谱硬度相关？
• RQ2 黑体组分通量与观测到的硬态之间存在何种关系？
• RQ3 为何不同的硬态在颜色-颜色图中形成不同的分支？
• RQ4 颜色-颜色图中观测到的梳状结构如何反映潜在的物理参数？
• RQ5 能否将传统的单维状态演化模型扩展为二维描述？

主要发现

• XTE J1550-564的颜色-颜色图呈现出梳状拓扑结构，其中软态构成中轴，硬态构成梳齿。
• 在硬分支上检测到1–18 Hz和100–285 Hz的QPO，而在软分支及其附近检测到15–18 Hz的QPO。
• 硬分支上高低频QPO的频率彼此相关，并与光谱硬度相关。
• 硬态之间差异主要与黑体组分的通量相关。
• 二维状态空间最适宜由两个独立参数描述：通过吸积盘的吸积速率和康普顿化区域的大小。
• 观测行为支持二维模型而非传统的单维状态演化模型，其中软态对应于中轴区域，硬态对应于梳齿区域。