论文标题
UGC 3223中的X射线光度依赖性“更换”现象
An X-ray Luminosity-dependent "Changing-look" Phenomenon in UGC 3223
论文作者
论文摘要
在当前阶段，活性银河核（AGN）中罕见的“更换”（Cl）现象的性质仍在争论中。我们在这里提出\ IT Swift/\ rm Xrt和UGC \，3223的UVOT随访观察结果，这是一种新发现的重复CL-AGN，其类型过渡为$ \ MATHRM {S1.5 \ rightArrow S2 \ rightArrow S2 \ rightArrow S1.8} $在大约30年的时间内发生。通过比较先前在\ rm rosat \ rm All-Sky调查中报告的值以及在第二个Swift-XRT点源目录中，我们清楚地发现X射线通量紧密遵循光谱跃迁，其中光谱类型接近Seyfert 1类型，与较高的X射线磁通相关。然而，在物体的Cl现象中发现了不变的X射线光谱形状。 $ \ sim2 \ times10^{ - 4} $的Eddington比率极低，可以从其Seyfert 2状态的X射线光度中获得，这表明在解释CL现象时，这表明了磁盘范围广泛的区域模型。与先前的\ it galex \ rm nuv观察值相比，总紫外线发射的变化未揭示，因为紫外线图像$ \ sim90 $ \％uv uv发射来自主机银河系中的密集恒星形成。
The nature of the rare "Changing-look" (CL) phenomenon in active galactic nuclei (AGNs) is still under debate at current stage. We here present \it Swift/\rm XRT and UVOT follow-up observations of UGC\,3223, a newly discovered repeat CL-AGN with type transitions of $\mathrm{S1.5\rightarrow S2 \rightarrow S1.8}$ occurring in a period of about 30 years. By comparing the values previously reported in the \it ROSAT \rm All-sky Survey and in the second Swift-XRT Point Source catalog, we clearly find that the X-ray flux tightly follows the optical spectral transition, in which a spectral type closer to a Seyfert 1 type is associated with a higher X-ray flux. An invariable X-ray spectral shape is, however, found in the CL phenomenon of the object. An extremely low Eddington ratio of $\sim2\times10^{-4}$ can be obtained from the X-ray luminosity for its Seyfert 2 state, which suggests a favor of the disk-wind broad-line region model in explaining the CL phenomenon. A variation of the total UV emission is not revealed when compared to the previous \it GALEX \rm NUV observation, since the UVOT images indicate that $\sim90$\% UV emission comes from the intensive star formation in the host galaxy.
