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arXiv 2604.22643astro-ph.HE
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辐射反馈作为黑洞X射线双星准周期振荡活动的驱动因素

Radiative feedbacks as drivers for quasi-periodic-oscillation activity in black-hole X-ray binaries

National and Kapodistrian University of Athens(雅典国立卡波迪斯特里安大学)

Apostolos Mastichiadis

AI总结:

本文研究了辐射反馈是否能产生具有QPO谱时特性的时间循环,通过一区辐射框架建模电子和光子的时变动能方程,发现当电子冷却主要由吸积盘重新处理的软光子主导时,盘-冠系统会发生极限振荡,重现了观测到的类型C QPO特性。

摘要:

黑洞X射线双星(BHXRBs)在硬和硬中间光谱状态下,其X射线功率谱常表现出显著的类型C准周期振荡(QPOs)。尽管有大量观测和理论研究,这些振荡的物理机制仍未确定。BHXRBs中的盘-冠系统存在辐射耦合,因为来自冠的硬X射线可通过吸积盘重新处理并重新发射为软光子,这些光子有助于冷却冠电子。本文旨在研究这种反馈是否能产生具有QPO谱时特性的极限循环。我们使用一区辐射框架建模冠部发射,并求解电子和光子的时变动能方程。电子通过某种未指定过程获得能量,并通过逆康普顿散射软光子冷却,这些光子来自(i)吸积盘和(ii)盘对冠产生硬辐射的重新处理。当电子冷却主要由吸积盘重新处理的软光子主导时,盘-冠系统会发生极限振荡。对于部分模型参数,这些振荡重现了BHXRBs中观测到的类型C QPOs的关键特性。振荡频率取决于冠半径和能量过程时间尺度,而所产生的X射线谱可由幂律描述,延伸至~10-100 keV能量。这些计算确认并扩展了之前简化处理得到的半解析结果。由于模型的自相似性质,结果可轻易扩展到其他吸积系统,如活动星系核。

英文摘要:

Black-hole X-ray binaries (BHXRBs) in the hard and hard-intermediate spectral states commonly exhibit prominent type-C quasi-periodic oscillations (QPOs) in their X-ray power spectra. Despite extensive observational and theoretical efforts, the physical mechanism responsible for these oscillations has not yet been firmly established. The disk-corona system in BHXRBs is radiatively coupled, as hard X-ray emission from the corona can be reprocessed by the accretion disk and re-emitted as soft photons that contribute to cooling the coronal electrons. Aim of the present study is to examine whether this feedback can give rise to limit cycles having the spectro-temporal properties of QPOs. We model the coronal emission using a one-zone radiation framework and solve the time-dependent kinetic equations for electrons and photons. Electrons are energized by some unspecified process and cool via inverse Compton scattering of soft photons originating from (i) the accretion disk and (ii) disk reprocessing of the hard radiation produced in the corona. When electron cooling is dominated by soft photons reprocessed in the accretion disk, the disk-corona system undergoes limit-cycle oscillations. For a subset of the model parameters, these oscillations reproduce key properties of type-C QPOs observed in BHXRBs. The oscillation frequency depends on the coronal radius and on the energization timescale, while the resulting X-ray spectra are well described by power laws extending up to energies of ~ 10-100 keV. These calculations confirm and extend earlier semi-analytical results obtained with simplified treatments. Owing to the scale-invariant nature of the model, the results can be readily extrapolated to other accreting systems, such as Active Galactic Nuclei.

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