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Variability and the X-ray/UV?ratio of active galactic nuclei

机译：活性银河核的变异性和X射线/紫外线比

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Context. The observed relation between the X-rayradiation from active galactic nuclei, originating in the corona, andthe optical/UVradiation from the disk is usually described bythe anticorrelation between the UVto X-ray slope and the UVluminosity. Many factors can affect this relation,including: i) enhanced X-ray emission associated with the jets ofradio-loud AGNs, ii) X-ray absorption associated with theUVbroad absorption line (BAL) outflows, iii) other X-rayabsorption not associated with BALs, iv) intrinsic X-ray weakness, v)UVand X-ray variability, and non-simultaneity ofUVand X-ray observations. The separation of these effectsprovides information about the intrinsic relation and its dispersion, constraining models of disk-coronacoupling. Aims. We use simultaneous UV/X-ray observations toremove the influence of non-simultaneous measurements from the relation.Methods. We extract simultaneous data from thesecond XMM-Newton serendipitous source catalogue(XMMSSC) and the XMM-Newton Optical MonitorSerendipitous UVSource Survey catalogue (XMMOMSUSS), andderive the single-epoch indices. We use ensemble structure functions to analyse multi-epochdata. Results. We confirm the anticorrelation of with ,and do not find any evidence of a dependence of on z. The dispersion in our simultaneous data ()is not significantly smaller than in previous non-simultaneous studies,suggesting that ``artificial variability'' introduced by non-simultaneity is not the main cause ofdispersion. ``Intrinsic variability'', i.e., the true variability of the X-ray to opticalratio, is instead important, and accounts for 30% of the total variance, or more.``Inter-source dispersion'', due to intrinsic differences in theaverage values from source to source, is also important. The dispersionintroduced by variability is mostly caused by the long timescalevariations, which are expected to be driven by the optical variations. Key words: surveys - galaxies: active -quasars: general - X-rays: galaxies
机译：上下文。通常通过紫外线到X射线斜率与紫外线发光度之间的反相关关系来描述观察到的来自活动银河核的X射线辐射（源自电晕）与来自盘的光学/ UV辐射之间的关系。许多因素都会影响这种关系，包括：i）与大声AGN射流相关的X射线发射增强; ii）与宽吸收线（BAL）流出相关的X射线吸收; iii）与X射线不相关的其他X射线吸收BAL，iv）X射线固有的弱点，v）UV和X射线的可变性，以及UV和X射线观察的非同步性。这些效应的分离提供了关于固有关系及其分散的信息，从而约束了磁盘冠状耦合的模型。目的我们使用同时​​进行的UV / X射线观察来消除关系中非同时测量的影响。我们从第二个XMM-牛顿偶发源目录（XMMSSC）和XMM-牛顿光学监测仪Serendipitous UVSource调查目录（XMMOMSUSS）中提取同步数据，并得出单历时索引。我们使用集合结构函数来分析多历元数据。结果。我们确认与的反相关性，并且未找到任何依赖于z的证据。我们同时数据中的离散度（）并不比以前的非同步性研究小得多，这表明由非同步性引起的``人为可变性''不是离散的主要原因。相反，``内在变异性''（即X射线相对于光学比的真实变异性）很重要，并占总变异性的30％或更多.``由于内在差异，``源间色散''在源之间的平均值上也很重要。可变性引起的色散主要是由长时间尺度的变化引起的，预期该变化是由光学变化驱动的。关键词：调查-星系：活动-类星体：一般-X射线：星系

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