After decades of searching, cosmological time dilation was recently identified in the timescale of variability seen in distant quasars. Here, we expand on the previous analysis to disentangle this cosmological signal from the influence of the properties of the source population, specifically the quasar bolometric luminosity and the rest-frame emission wavelength at which the variability was observed. Furthermore, we consider the potential influence of the evolution of the quasar population over cosmic time. We find that a significant intrinsic scatter of 0.288 +- 0.021 dex in the variability timescales, which was not considered in the previous analysis, is favoured by the data. This slightly increases the uncertainty in the results. However, the expected cosmological dependence of the variability timescales is confirmed to be robust to changes in the underlying assumptions. We find that the variability timescales increase smoothly with both wavelength and bolometric luminosity, and that black hole mass has no effect on the variability timescale once rest wavelength and bolometric luminosity are accounted for. Moreover, if the standard cosmological model is correct, governed by relativistic expansion, we also find very little cosmological evolution in the intrinsic variability timescales of distant quasars.

翻译：经过数十年的探索，宇宙学时间膨胀现象最近在遥远类星体的光变时标中被识别出来。本文在先前分析的基础上进行扩展，旨在将这一宇宙学信号与源群体特性的影响分离开来，具体而言，即类星体的热光度以及观测到光变的静止系发射波长。此外，我们还考虑了类星体群体在宇宙时间尺度上演化的潜在影响。我们发现，数据倾向于支持光变时标存在0.288 +- 0.021 dex的显著内禀弥散，这一因素在之前的分析中未被考虑。这略微增加了结果的不确定性。然而，光变时标预期的宇宙学依赖性被证实对基本假设的变化具有稳健性。我们发现，光变时标随波长和热光度平滑增加，并且一旦考虑了静止波长和热光度，黑洞质量对光变时标没有影响。此外，如果由相对论性膨胀主导的标准宇宙学模型是正确的，我们还发现遥远类星体的内禀光变时标在宇宙学演化上变化甚微。