活动星系核功率谱分析及TeV耀变体极快X射线光变分析

发布时间：2018-03-07 15:27

本文选题：活动星系核　切入点：光变　出处：《中国科学技术大学》2016年硕士论文　论文类型：学位论文

【摘要】：活动星系核(Active Galactic Nuclei; AGNs)是由星系中心超质量黑洞的吸积驱动的。黑洞吸积天体的一个重要特征是它们的辐射在各个电磁波段都存在持续的光变,并且这种光变在不同的时间尺度上都有表现。活动星系核的光变不仅可以作为一种工具帮助我们了解黑洞周围的结构分布,而且通过对光变性质的研究可以对吸积物理提供限制。研究光变的一个重要途径是基于傅里叶方法的功率谱分析。人们使用周期图(periodogram)对内在物理过程的功率谱进行测量。由于活动星系核本征功率谱的性质以及天文观测采样模式的限制,周期图受到多种系统性的偏差影响,其中描述短时标光变的高频功率谱容易受到一种叫做红噪声泄露的系统偏差的严重影响。由于红噪声泄露的问题并没有理想的解决途径,我们提出一种全新的方法对红噪声泄露进行描述。我们称之为归一化泄露谱,它能描述红噪声泄露的严重程度在不同频率上的分布,并能从泄露的严重程度上限制活动星系核光变的本征功率谱。我们提出了一种蒙特卡洛方法来实现这一目标。根据活动星系核的统一模型,当一个活动星系核存在射电喷流,并且一个喷流的喷射方向刚好朝向地球的时候,这类活动星系核就成为观测上的耀变体(blazar)。我们称一类在极高能7-ray (Very High Energy;100GeV)探测到辐射的耀变体为TeV耀变体。这类天体的能谱(Spectral Energy Distribution; SED)通常在X射线波段存在一个宽的同步辐射峰,这部分辐射直接产生于喷流中最高能的相对论性电子,所以通常有最短的光变时标。通过寻找这些TeV耀变体在X射线波段最快光变耀发(flare),我们可以限制辐射区的物理性质,例如磁场强度、多普勒因子、物理尺度等。我们在RXTE对TeV耀变体的所有观测中,找到了3个新的小时时标以下的X射线耀发,其中最快的光变时标(上升)小于半分钟,这个事件是现在所有AGN观测中最快的光变,并且其对应的辐射区尺度上限小于黑洞视界。
[Abstract]:Active Galactic Nuclei; AGNs) are driven by accretion of supermassive black holes in the center of galaxies. An important feature of black hole accretion objects is that their radiation varies continuously in all electromagnetic waves. And this kind of light change shows up at different time scales. Light change in AGNs can not only be used as a tool to help us understand the structural distribution around black holes. One of the important ways to study photovoltaics is the power spectrum analysis based on Fourier method. People use period diagram to analyze the power spectrum of intrinsic physical process. Line measurements. Due to the nature of the intrinsic power spectrum of active galactic nuclei and the limitations of astronomical observation sampling models, The periodic diagram is influenced by many systematic deviations, in which the high frequency power spectrum describing the short-time scalar optical variation is vulnerable to the serious influence of a system bias called red noise leakage. There is no ideal solution to the problem of red noise leakage. We propose a new method to describe the red noise leakage. We call it the normalized leakage spectrum, which can describe the distribution of the severity of the red noise leakage at different frequencies. We propose a Monte Carlo method to achieve this goal. According to the unified model of AGNs, when an active galactic nucleus exists a radio jet, And when a jet is just heading towards the Earth, This type of active galactic nucleus is known as the observational blazar.We call a class of radiations detected at extremely high energy 7-ray very High energy 100GeV as TeV's. The spectral spectrum of these objects is spectral Energy distribution; SED) usually has a wide synchrotron radiation peak in the X-ray band. This part of the radiation is generated directly from the relativistic electrons at the highest energy in the jet, so there is usually the shortest light-dependent time scale. By looking for these TeV variants to flare the fastest flares in the X-Ray band, we can limit the physical properties of the radiation region. For example, magnetic field intensity, Doppler factor, physical scale, etc. We have found three X-ray flares below the new hour scale in all RXTE observations of the TeV yaw, the fastest of which is less than half a minute. This event is the fastest light change of all AGN observations and the upper limit of the corresponding radiation area is smaller than the black hole event horizon.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P157.6

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