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

黑洞的吸积是根据一种很好观察到的现象学进行的，然而，目前很少有细节被很好地理解。其中一个最不为人所知的方面是高频准周期振荡（QPOs）的普遍性和性质，在黑洞双星（BHBs）和只有两个活动星系核（AGN）的高吸积率中可以看到。这些qpo的频率表明，它们可能起源于靠近黑洞的强引力区域，在那里广义相对论的影响占主导地位。考虑到QPO频率的大规模缩放，AGN允许对这些QPO进行更好（延长）的观察，但这些QPO非常罕见。该项目的第一部分是通过对数据进行能量分割，并应用一种新的算法来检测噪声数据中的相干信号，来搜索XMM-Newton数据集中最亮的AGN （PG qso）的QPO候选数据。这项技术还将扩展到bhb（主要是RXTE）上的大量档案，以便发现更多的qpo，了解它们出现时的流行程度和来源的性质。该项目的后半部分还将涉及使用协方差谱来揭示潜在发射成分的变化如何可能导致这些QPOs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.