CSS和ZTF光变曲线上quasar 4C 50.43中不同周期的光学QPOs
Optical QPOs with different periodicities in CSS and ZTF light curves of the quasar 4C 50.43
AI总结：
研究发现quasar 4C 50.43在CSS和ZTF光变曲线中存在不同周期的光学QPOs，表明红噪声对周期性有显著影响，需谨慎应用QPOs于具有强AGN变异性系统。
摘要：
长期以来，周期为数百到数千天的光学准周期震荡（QPOs）已被接受为标志中心亚pc双黑洞系统（BBHs）在宽线活动星系核（BLAGN）中的指示物。然而，迄今为止尚无直接报告表明此类报告的光学QPOs在不同时期是否具有恒定的周期性。在此，基于不同方法应用于4C 50.43在不同时期光变曲线的光变曲线，发现CSS V波段光变曲线上周期为1124天的光学QPOs，而在ZTF g/r波段光变曲线上检测到较短的周期为513天的QPOs。尽管这两个周期近谐波比为2:1，但它们在ZTF光变曲线的 Lomb-Scargle 周期图中没有同时检测到，这表明它们不太可能具有谐波关系。考虑了可能的解释因素，特别是CSS和ZTF光变曲线之间的时间覆盖、信噪比和时间步长的不同，以及与内在AGN变异性相关的红噪声的影响。我们的分析显示，红噪声对4C 50.43中不同周期性有显著影响，支持我们之前的模拟。本文的结果强烈表明，对于具有强内在AGN变异性BLAGN，应用确定的光学QPOs应谨慎。
英文摘要：
Long-standing optical quasi-periodic oscillations (QPOs) with periodicity of hundreds to thousands of days have been accepted as indicators for central sub-pc binary black hole systems (BBHs) in broad line active galactic nuclei (BLAGN). However, there are so far no direct reports on whether such reported optical QPOs have their periodicities constant in different periods. Here, based on different methods applied to light curves of 4C 50.43 in different periods, optical QPOs with periodicity of 1124days was detected in the CSS V-band light curve, while a shorter periodicity of 513days was detected in the ZTF g/r band light curves. Despite the two periodicities near-harmonic 2:1 ratio, their absence of simultaneous detection in the lomb-scargle periodograms of the ZTF light curves suggests that they are unlikely to be harmonically related. Potential factors were considered to explain these two distinct periodicities, especially different temporal coverage, signal-to-noise ratio and time steps between the CSS and ZTF light curves, as well as the effects of red noises related to intrinsic AGN variability. Our analysis shows that red noises have strong influence on the different periodicities in 4C 50.43 supporting our previous simulations. The results in this manuscript strongly indicate that it should be cautioned for applications of determined optical QPOs in BLAGN having strong intrinsic AGN variability.
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