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arXiv 1406.3845astro-ph.HE
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银河系黑洞光谱和时间特性的数值模拟

Numerical Simulation Of Spectral And Timing Properties Of Galactic Black Holes

Sudip Kumar Garain

摘要:

一个黑洞的吸积可以同时具有开普勒分量和次开普勒分量。我们认为最一般的吸积流配置,即,两个组件的平流(TCAF)中的开普勒磁盘是沉浸在一个低的角动量,吸积子开普勒晕组件周围的黑洞。来自开普勒分量的低能(软)光子和亚开普勒分量中的热电子通过康普顿化或逆康普顿化过程交换它们的能量。在次开普勒分量中,通常由于离心力而形成激波。激波后区域被称为离心压力主导的边界层(CENBOL)。自1995年Chakrabarti和Titarchuk提出TCAF模型以来,人们对TCAF的光谱和时间特性进行了广泛的研究,主要是使用解析和一些与时间相关的数值模拟。这些发现是理解黑洞候选者的几个观测特征的关键输入。在本论文中,我们使用数值模拟的方法,严格地证明了TCAF模型的一些结构。在本论文的工作中,我们第一次考虑了开普勒流和次开普勒流的存在。开普勒盘位于赤道平面上,并且是标准盘,从该标准盘发射具有多色黑体光谱的低能光子。利用有限差分程序,采用总变差递减(TVD)原理,模拟了次开普勒晕的流体动力学和热性质。利用蒙特卡罗程序模拟了光子与超热电子之间的康普顿化过程。然后将这两个代码耦合,并将所产生的局部加热和冷却包括在耦合代码中。利用这个程序,我们研究了TCAF的频谱和定时特性。

英文摘要:

A black hole accretion may have both the Keplerian and the sub-Keplerian components. We consider the most general accretion flow configuration, namely, two-component advective flow (TCAF) in which the Keplerian disk is immersed inside a low angular momentum, accreting sub-Keplerian halo component around a black hole. Low energy (soft) photons from the Keplerian component and hot electrons in the sub-Keplerian component exchange their energy through Comptonization or inverse-Comptonization processes. In the sub-Keplerian component, a shock is generally formed due to the centrifugal force. The post-shock region is known as the CENtrifugal pressure dominated BOundary Layer (CENBOL). The spectral and the timing properties of TCAF have been extensively studied using mostly analytical and some time dependent numerical simulations since the model was proposed by Chakrabarti & Titarchuk in 1995. The findings are the key inputs of understanding several observed features of black hole candidates. In this thesis, using numerical simulation, we rigorously prove some of the conjectures of the TCAF model. In the work presented in this thesis, we have considered for the first time the presence of both the Keplerian and the sub-Keplerian flow in a single simulation. The Keplerian disk resides on the equatorial plane and is the standard disk from which low energy photons having multi-color blackbody spectrum is emitted. The hydrodynamics as well as the thermal properties of the sub-Keplerian halo are simulated using a finite difference code which uses the principle of total variation diminishing (TVD). The Comptonization between the photons and the hot electrons is simulated using a Monte Carlo code. These two codes are then coupled and the resulting localized heating and cooling are included in the coupled code. Using this code, we study the spectral and timing properties of the TCAF.

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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