Inconsistent conclusions are obtained from recent active galactic nuclei (AGNs) accretion disk inter-band time-lag measurements. While some works show that the measured time lags are significantly larger (by a factor of ∼3) than the theoretical predictions of the Shakura & Sunyaev disk (SSD) model, others find that the time-lag measurements are consistent with (or only slightly larger than) that of the SSD model. These conflicting observational results might be symptoms of our poor understanding of AGN accretion physics. Here we show that sources with larger-than-expected time lags tend to be less luminous AGNs. Such a dependence is unexpected if the inter-band time lags are attributed to the light-travel-time delay of the illuminating variable X-ray photons to the static SSD. If, instead, the measured inter-band lags are related not only to the static SSD but also to the outer broad emission-line regions (BLRs; e.g., the blended broad emission lines and/or diffuse continua), our result indicates that the contribution of the non-disk BLR to the observed ultraviolet/optical continuum decreases with increasing luminosity (L), i.e., an anti-correlation resembling the well-known Baldwin effect. Alternatively, we argue that the observed dependence might be a result of coherent disk thermal fluctuations as the relevant thermal timescale, τ _TH ∝ L ^0.5. With future accurate measurements of inter-band time lags, the above two scenarios can be distinguished by inspecting the dependence of inter-band time lags upon either the BLR components in the variable spectra or the timescales.

从最近的活动星系核 (AGN) 吸积盘带间时滞测量中获得了不一致的结论。虽然一些工作表明测量的时滞明显大于 Shakura & Sunyaev 磁盘 (SSD) 模型的理论预测（约 3 倍），但其他人发现时滞测量与（或仅略微）一致大于) SSD 型号。这些相互矛盾的观测结果可能是我们对 AGN 吸积物理学了解不足的症状。在这里，我们表明时间滞后大于预期的源往往是亮度较低的 AGN。如果带间时间滞后归因于照明可变 X 射线光子到静态 SSD 的光传播时间延迟，则这种依赖性是出乎意料的。如果相反，L )，即类似于众所周知的鲍德温效应的反相关。或者，我们认为观察到的依赖性可能是相关热时间尺度τ _TH ∝ L ^0.5的相干盘热波动的结果。随着未来对带间时滞的准确测量，可以通过检查带间时滞对可变光谱中的 BLR 分量或时间尺度的依赖性来区分上述两种情况。