Vol 21, No 8

X-ray spectral evolution in an X-ray changing-look AGN NGC 1365 with variable column density

Hao Liu, Qing-Wen Wu, Yong-Quan Xue, Ting-Gui Wang, Jun Yang, Heng-Xiao Guo, Zhi-Cheng He


Abstract X-ray changing-look active galactic nuclei (CL AGNs) are a subpopulation of AGNs, whose lineof-sight column densities increase/decrease within several years. The physical mechanism for the variation of column density is unclear. We reduce the X-ray data from XMM-Newton and NuSTAR observations for a CL AGN NGC 1365 with strong variation of column densities. The X-ray spectrum quickly softens as the X-ray luminosity increases and optical-to-X-ray spectral index also increases as increasing of optical luminosity. These results support that NGC 1365 also undergoes strong spectral evolution as that recently suggested for the optically selected CL AGNs with reappearance/disappearance of broad emission lines. Therefore, the variation of column density may be driven by the variable disk winds during the strong evolution of disk/corona.


Keywords galaxies: active — galaxies: Seyfert — quasars: emission lines — accretion, accretion disks

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