论文标题
NGC 5548的多波长功率光谱分析
Multiwavelength power-spectrum analysis of NGC 5548
论文作者
论文摘要
作为风暴运动的一部分，NGC 5548最近受到从NIR到X射线的密集监测。发现其圆盘发射滞后于观察到的X射线，而测得的时间滞后则随波长而增加。这些结果与假设AGN发射中的短期变异性是由积聚盘的X射线照明驱动的。在这项工作中，我们使用Storm活动的数据以及以前的Swift数据研究了NGC 5548的UV/光学和X射线发射的功率谱，以研究UV/光学和X射线变异性之间的关系并检查其与上图的一致性。我们证明，即使功率谱结果也与X射线照亮的标准圆盘兼容，其吸积率较低，但是细节并不完全与“τvsvsλ”关系建模的结果完全一致。差异表明，内盘可能被“温暖的电晕”覆盖，该圆盘不允许从内盘检测到紫外线/光学发射。最后，我们发现有力的证据表明NGC 5548的紫外线发射不是静止的。
NGC 5548 was recently monitored intensively from NIR to X-rays as part of the STORM campaign. Its disc emission was found to lag behind the observed X-rays, while the measured time lag was increasing with wavelength. These results are consistent with the assumption that short term variability in AGN emission is driven by the X-ray illumination of the accretion disc. In this work, we studied the power spectrum of UV/optical and X-ray emission of NGC 5548, using the data of the STORM campaign as well as previous Swift data, in order to investigate the relation between the UV/optical and X-ray variability and to examine its consistency with the above picture. We demonstrate that even the power spectrum results are compatible with a standard disc being illuminated by X-rays, with low accretion rates, but the details are not entirely consistent with the results from the modelling of the "τ vs λ" relation. The differences indicate that the inner disc might be covered by a "warm corona" which does not allow the detection of UV/optical emission from the inner disc. Finally, we found strong evidence that the UV emission of NGC 5548 is not stationary.
