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arXiv 2103.09675astro-ph.HE
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GRS 1915+105的可变日冕

A variable corona for GRS 1915+105

Konstantinos Karpouzas, Mariano Méndez, Federico García, Liang Zhang, Diego Altamirano, Tomaso Belloni, Yuexin Zhang

摘要:

大多数低质量X射线双星(LMXB)中低频准周期振荡(QPO)的模型解释了这些QPO的动力学性质。另一方面,近年来的混响模型,假设一个灯柱几何已经成功地解释了能量依赖的时间滞后的恒星质量黑洞和活动星系核的宽带噪声分量。我们最近表明,康普顿化可以解释在中子星(NS)LMXB中观察到的千赫(kHz)QPO的光谱定时特性。因此,值得探讨的是,同一系列的模型是否能成功地解释低频QPO。在这项工作中,我们使用康普顿化模型来研究BH LMXB GRS 1915+105中的C型QPO的相位滞后的频率依赖性。GRS 1915+105中QPO的相位滞后在约1.8Hz的QPO频率处进行从硬到软的转变。我们的模型表明,在高QPO频率下,约100-150 R_g的大日冕覆盖了大部分吸积盘,使吸积盘100%反馈控制,从而产生软滞后。随着所观察到的QPO频率的降低,电晕逐渐收缩到约3-17 R_g,并且在1.8 Hz时,到盘上的反馈变得低效,导致硬滞后。我们讨论了如何在吸积几何的变化影响的定时性质的C型QPO。

英文摘要:

Most models of the low frequency quasi periodic oscillations (QPOs) in low-mass X-ray binaries (LMXBs) explain the dynamical properties of those QPOs. On the other hand, in recent years reverberation models that assume a lamp-post geometry have been successfull in explaining the energy-dependent time lags of the broad-band noise component in stellar mass black-holes and active galactic nuclei. We have recently shown that Comptonisation can explain the spectral-timing properties of the kilo-hertz (kHz) QPOs observed in neutron star (NS) LMXBs. It is therefore worth exploring whether the same family of models would be as successful in explaining the low-frequency QPOs. In this work, we use a Comptonisation model to study the frequency dependence of the phase lags of the type-C QPO in the BH LMXB GRS 1915+105. The phase lags of the QPO in GRS 1915+105 make a transition from hard to soft at a QPO frequency of around 1.8 Hz. Our model shows that at high QPO frequencies a large corona of ~ 100-150 R_g covers most of the accretion disc and makes it 100% feedback dominated, thus producing soft lags. As the observed QPO frequency decreases, the corona gradually shrinks down to around 3-17 R_g, and at 1.8 Hz feedback onto the disc becomes inefficient leading to hard lags. We discuss how changes in the accretion geometry affect the timing properties of the type-C QPO.

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。

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