论文标题
来自MEXSAS2样品的主动银河核的单个光学变异性
Individual optical variability of Active Galactic Nuclei from the MEXSAS2 sample
论文作者
论文摘要
主动银河核（AGN）的大多数可变性研究基于集合分析。然而，为了将它们与内在的物理量相关联，对每个AGN的个体可变性属性进行估计很有趣。 Catalina Surveys数据释放2（CSDR2）提供了一个有用的数据集，该数据包包括$ \ sim500 $ $ \ sim500 $ $ $ $ $ $ $ $ \ sim500 $ $ $ $ \ sim500 $ $ $ \ sim500 $ $的反复观察到数百次。我们旨在研究最初包含在XMM XMM Serendipitous AGN样本2（MEXSAS2）中的795个AGN的单个光学变异性能。我们的目标包括：（i）寻找可变性与AGN物理量之间的相关性； （ii）将MEXSAS2的可变性特征的知识从X射线扩展到光学。我们使用结构函数（SF）来分析AGN通量变化。我们将SF建模为幂律，$ \ text {sf}（τ）= a \，（τ/τ_0）^γ$，我们计算其可变性参数。我们将V校正作为一个简单的工具引入，以正确量化每个源的其余框架中的可变性量。我们发现随着侧强度，光学和X射线光度的增加，可变性幅度的显着降低。我们获得了可变性幅度和红移（$ z $）之间本质上弱的正相关的指示。可变性幅度也与$α_\ text {ox} $正相关。 SF的斜率（$γ$）与Bolometric Luminosity $ L_ \ text {bol} $和/或与黑洞质量$ m_ \ text {bh} $相关。当将光学与X射线变异性属性进行比较时，我们发现X射线变异性振幅对于那些在光学中具有较大或较小可变性幅度的AGN大致相同。相反，光学中具有较高SF的AGN确实会在X射线中呈较陡的SF，反之亦然。
Most of the variability studies of active galactic nuclei (AGNs) are based on ensemble analyses. Nevertheless, it is interesting to provide estimates of the individual variability properties of each AGN, in order to relate them with intrinsic physical quantities. A useful dataset is provided by the Catalina Surveys Data Release 2 (CSDR2), which encompasses almost a decade of photometric measurements of $\sim500$ million objects repeatedly observed hundreds of times. We aim to investigate the individual optical variability properties of 795 AGNs originally included in the Multi-Epoch XMM Serendipitous AGN Sample 2 (MEXSAS2). Our goals consist in: (i) searching for correlations between variability and AGN physical quantities; (ii) extending our knowledge of the variability features of MEXSAS2 from the X-ray to the optical. We use the structure function (SF) to analyse AGN flux variations. We model the SF as a power-law, $\text{SF}(τ)=A\,(τ/τ_0)^γ$, and we compute its variability parameters. We introduce the V-correction as a simple tool to correctly quantify the amount of variability in the rest frame of each source. We find a significant decrease of variability amplitude with increasing bolometric, optical and X-ray luminosity. We obtain the indication of an intrinsically weak positive correlation between variability amplitude and redshift, $z$. Variability amplitude is also positively correlated with $α_\text{ox}$. The slope of the SF, $γ$, is weakly correlated with the bolometric luminosity $L_\text{bol}$ and/or with the black hole mass $M_\text{BH}$. When comparing optical to X-ray variability properties, we find that X-ray variability amplitude is approximately the same for those AGNs with larger or smaller variability amplitude in the optical. On the contrary, AGNs with steeper SF in the optical do present steeper SF in the X-ray, and vice versa.
