论文标题
类星体光谱与可变性之间的关系
The relation between quasars' optical spectra and variability
论文作者
论文摘要
这项工作旨在找到类星体的光学变异性和光谱特征之间的关系，以揭示随机变化背后的规律性。众所周知，Quasar的FEII/HBETA通量比和[OIII] 5007的等效宽度是负相关的，称为EIGENVECTOR 1。在这项工作中，我们可视化了这项eigenvector 1（EV1）平面上的位置之间的关系，以及它们在〜10年后如何改变了它们的光泽。我们使用不同的类星体样品进行了三个分析。第一个分析表明，使用13,438个Sloan Digital Sky Survey Quasars，它们在EV1平面上的分布之间的关系以及它们改变了亮度的程度。该结果表明了以后亮度变化与EV1平面上的位置明显相关。在第二个分析中，我们绘制了报道的EV1平面上的更换外观（状态）类星体。该结果表明，EV1平面上的位置对应于每个源的活性水平，它们的明亮或昏暗状态分布在相反的侧面除以典型的类星体分布。在第三个分析中，我们使用带有多个期间光谱的源检查了EV1平面上的过渡向量。该结果表明，亮度和调光源在相似的路径上移动，它们变成了与相反活动水平相对应的位置。我们还发现，这种趋势与经验规则相反，即RFEII与Eddington的比例正相关，Eddington的比例是根据大量类星体的趋势提出的。从所有这些分析中，可以表明类星体倾向于在EV1平面上分布脊之间振荡。它们每个都对应于一个昏暗的状态和明亮的状态。光学变化中的这种趋势表明，预计明显的亮度变化（例如更换类星体）将重复。
This work aimed to find the relationship between quasars' optical variability and spectral features to reveal the regularity behind the random variation. It is known that quasar's FeII/Hbeta flux ratio and equivalent width of [OIII]5007 are negatively correlated, called Eigenvector 1. In this work, we visualized the relationship between the position on this Eigenvector 1 (EV1) plane and how they had changed their brightness after ~10 years. We conducted three analyses using different quasar samples each. The first analysis showed the relation between their distributions on the EV1 plane and how much they had changed brightness, using 13,438 Sloan Digital Sky Survey quasars. This result shows how brightness changes later are clearly related to the position on the EV1 plane. In the second analysis, we plotted the sources reported as Changing-Look(State) Quasars on the EV1 plane. This result shows that the position on the EV1 plane corresponds activity level of each source, the bright or dim state of them are distributed on the opposite sides divided by the typical quasar distribution. In the third analysis, we examined the transition vectors on the EV1 plane using sources with multiple-epoch spectra. This result shows that the brightening and dimming sources move on the similar path and they turn into the position corresponding to the opposite activity level. We also found this trend is opposite to the empirical rule that RFeII positively correlated with the Eddington ratio, which has been proposed based on the trends of a large number of quasars. From all these analyses, it is indicated that quasars tend to oscillate between both sides of the distribution ridge on the EV1 plane; each of them corresponds to a dim state and a bright state. This trend in optical variation suggests that significant brightness changes, such as Changing-Look quasars, are expected to repeat.
