活动星系核紫外FeII发射线的发射区和激发机制研究

FeII emission lines are one of the main features of active galacitic nucleus (AGNs) in the ultraviolet(UV) to the optical bands, while the emitting regions and the excitation mechanisms of FeII emission lines are still unclear. The broad-band shape of FeII was usually employed in previous papers to constrain their emitting regions and excitation mechanisms, however, no clear conclusion was drawn. In this project, the strong FeII emission multiplets in the UV band will be employed to constrain the emitting regions and the excitation mechanisms of FeII emission lines. Based on our existing studies, we will find those AGNs with these strong FeII emission multiplets in the spectral database of Sloan Digital Sky Survey. The FeII-emitting regions may be constrained by studying the relationships between the properties of the FeII emission multiplets and the intrinsic parameters of AGNs (e.g. luminosity, black hole masses and Eddingtion ratio) as well as the properties of other emission lines. Then we will carry out simulations to reconstruct the FeII emission spectra of different excitation mechanisms under different physical parameters using CLOUDY and constrain the excitation mechanisms of FeII emission lines by comparing with the observed sample mentioned above. Simultaneously, the follow-up observations of these AGNs will be performed using the domestic 2.4-meter and 2.16-meter telescopes. Such data will be used to search for the variabilities of the FeII emission multiplets, which will later be used to put further constraints on the models of the excitation mechanisms of FeII emission lines.

FeII发射线是活动星系核紫外到光学波段最主要的特征之一，然而其发射区和激发机制还不清楚。前人的工作主要是根据宽波段FeII谱形来限制FeII发射区和激发机制，但效果不理想。本项目拟利用一些强紫外FeII发射线簇(2400、2600、2750埃）来限制FeII发射区和激发机制。基于我们目前已有的研究基础，我们将在斯隆数字巡天的光谱数据库中找出具有这些强FeII发射线簇的活动星系核，通过研究FeII发射线簇的性质与活动星系核的本征物理量（如：光度、黑洞质量和吸积率）及其他发射线的性质之间的关系限制FeII发射区。然后，我们将用CLOUDY模拟各种激发机制在不同物理条件下的FeII发射谱，通过与上述观测样本进行比较，限制FeII的激发机制。同时，我们还将利用国内的2.4米和2.16米望远镜对这些源进行后续观测。这些数据可以用来搜寻紫外FeII发射线簇的光变，进一步限制FeII发射线的激发机制。

丰富的紫外、光学发射线是类星体的定义特征之一，尤其是FeII发射线覆盖整个紫外-光学波段，然而其发射区还不清楚。我们从斯隆数字巡天的海量光谱库中选出一些FeII发射线很强的类星体，并对其中几个进行后续的光谱监测，测得了其中一个FeII发射线光变相对于连续谱光变的时间延迟，确定了FeII的发射区大小，并根据其它发射线的时间延迟和线宽测量了其中心黑洞质量。通过比较不同发射线的轮廓，获得它们发射区的信息，讨论了基于各种发射线来估计黑洞质量的系统性偏差问题。我们发现一个活动星系核中的外流可以同时产生蓝移的发射线和吸收线，并基于CLOUDY模拟证实这一观点，并由此确定其发射区的大小和物理条件。此外，还开展了超新星的观测研究。在项目支持下，发表了6篇SCI论文。