Unravelling accretion flows in AGN and binaries using their complex variability patterns

黑洞的吸积过程是根据一个观察良好的现象学进行的，然而，目前对其中的细节还知之甚少。最不被了解的一个方面是高频准周期振荡(QPO)的普遍性和性质，在黑洞双星(BHB)和只有两个活动星系核(AGN)中可以看到高吸积率的QPO。这些QPO的频率表明，它们很可能起源于黑洞附近的强引力区域，在那里广义相对论效应占主导地位。考虑到QPO频率的质量比例，AGN允许更好(长期)地观察这些QPO，但却是极其罕见的。该项目的第一部分是搜索最亮活动星系核(PG类星体)的XMM-牛顿数据集，通过对数据进行能量切片并应用一种新的算法来检测噪声数据中的相干信号，以寻找QPO候选。这项技术还将推广到BHBs(主要是RXTE)上的大量档案，以努力发现更多的QPO，了解它们的普遍性和出现时来源的性质。该项目的后半部分还将涉及利用协方差谱来揭示排放的基本成分的变化可能如何导致这些准初级目标的出现。

Accretion onto black holes proceeds according to a well observed phenomenology, however, little of the details are presently well understood. One of the least understood aspects is the prevalence and nature of high frequency quasi-periodic oscillations (QPOs), seen at high accretion rates in black hole binaries (BHBs) and only two active galactic nuclei (AGN). The frequency of these QPOs indicates that they likely originate in the region of strong gravity close to the black hole, where effects of general relativity are dominant. Given the mass scaling of the QPO frequencies, AGN allow for a much better (protracted) view of these QPOs yet are extreme rarities. Part 1 of the project is to search the XMM-Newton datasets of the brightest AGN (the PG QSOs) for QPO candidates by energy-slicing the data and by applying a new algorithm to detect coherent signals in noisy data. This technique will also be extended to the vast archives on BHBs (principally RXTE) in an effort to discover more QPOs, understand their prevalence and the nature of the sources when they appear. The latter part of the project will also involve use of the covariance spectrum to unravel how changes in the underlying components of emission may be responsible for the appearance of these QPOs.