论文标题
在〜16年的基线上的极端变异性的光曲线表征
Characterization of Optical Light Curves of Extreme Variability Quasars Over a ~16-yr Baseline
论文作者
论文摘要
我们研究了〜900个极端变异性类星体（EVQ，最大磁通变化超过1 mag）的光光曲线 - 主要探究了从增强盘的可变发射，使用SDSS Stripe 82，Panstarrs -1和Dark Energy Survey的公共数据，在观察到的基线〜16年中的最大通量变化。我们将EVQ的多年长期光曲线分类为三类，以降低平滑度的顺序：单调降低或增加（3.7％），单次宽峰和倾角（56.8％）以及更复杂的模式（39.5％）。单调病例的稀有性表明，驱动极端光学可变性的主要机制在时间标准中的运行时间不超过几年。模拟的光曲线具有阻尼的随机步行模型，通常不足以预测的前两个类别，长期趋势更顺畅。尽管这些EVQ的长期行为不同，但长期趋势对类星体的物理特性（例如它们的亮度，BH质量和爱丁顿的比率）几乎没有依赖性。在这些EVQ的多年时间尺度上，光通量变化的较大动态范围使我们能够探索短期（<6个月）可变性与整个十年基线的季节性平均通量之间的合奏相关性（RMS-MEAN-MEAN-MEAN-MEAN-MEAN-MEAN FRUX关系）。我们发现，与X射线变异性研究的结果不同，线性短期通量变化并不能随季节性平均通量而扩展，这表明不同的机制可以驱动促进磁盘排放的短期闪烁和长期极端变化。最后，我们提出了16个EVQ的样本，其中简单的微透镜模型可以很好地拟合光曲线中的大约钟形大幅度变化。
We study the optical light curves - primarily probing the variable emission from the accretion disk - of ~ 900 extreme variability quasars (EVQs, with maximum flux variations more than 1 mag) over an observed-frame baseline of ~ 16 years using public data from the SDSS Stripe 82, PanSTARRS-1 and the Dark Energy Survey. We classify the multi-year long-term light curves of EVQs into three categories roughly in the order of decreasing smoothness: monotonic decreasing or increasing (3.7%), single broad peak and dip (56.8%), and more complex patterns (39.5%). The rareness of monotonic cases suggests that the major mechanisms driving the extreme optical variability do not operate over timescales much longer than a few years. Simulated light curves with a damped random walk model generally under-predict the first two categories with smoother long-term trends. Despite the different long-term behaviors of these EVQs, there is little dependence of the long-term trend on the physical properties of quasars, such as their luminosity, BH mass, and Eddington ratio. The large dynamic range of optical flux variability over multi-year timescales of these EVQs allows us to explore the ensemble correlation between the short-term (< 6 months) variability and the seasonal-average flux across the decade-long baseline (the rms-mean flux relation). We find that unlike the results for X-ray variability studies, the linear short-term flux variations do not scale with the seasonal-average flux, indicating different mechanisms that drive the short-term flickering and long-term extreme variability of accretion disk emission. Finally, we present a sample of 16 EVQs, where the approximately bell-shaped large amplitude variation in the light curve can be reasonably well fit by a simple microlensing model.
