X-ray quasi-periodic oscillations (QPOs) in AGN allow us to probe and understand the nature of accretion in highly curved space-time, yet the most robust form of detection (i.e. repeat detections over multiple observations) has been limited to a single source to-date, with only tentative claims of single observation detections in several others. The association of those established AGN QPOs with a specific spectral component has motivated us to search the XMM-Newton archive and analyse the energy-resolved lightcurves of 38 bright AGN. We apply a conservative false alarm testing routine folding in the uncertainty and covariance of the underlying broad-band noise. We also explore the impact of red-noise leak and the assumption of various different forms (power-law, broken power-law and lorentzians) for the underlying broad-band noise. In this initial study, we report QPO candidates in 6 AGN (7 including one tentative detection in MRK 766) from our sample of 38, which tend to be found at characteristic energies and, in four cases, at the same frequency across at least two observations, indicating they are highly unlikely to be spurious in nature.

中文翻译：

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在 AGN 中寻找能量分辨的准周期振荡

AGN 中的 X 射线准周期振荡 (QPO) 使我们能够探测和理解高度弯曲时空中的吸积性质，但最稳健的探测形式（即多次观测的重复探测）仅限于单个迄今为止的来源，在其他几个中只有一次观察检测的暂定声明。那些已建立的 AGN QPO 与特定光谱分量的关联促使我们搜索 XMM-牛顿档案并分析 38 个明亮 AGN 的能量分辨光曲线。我们在潜在宽带噪声的不确定性和协方差中应用了保守的误报测试例程折叠。我们还探讨了红噪声泄漏的影响以及对潜在宽带噪声的各种不同形式（幂律、破坏幂律和洛伦兹）的假设。