English

An X-ray Luminosity-dependent "Changing-look" Phenomenon in UGC 3223

Astrophysics of Galaxies 2020-07-30 v1 High Energy Astrophysical Phenomena

Abstract

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 S1.5S2S1.8\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 2×104\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 90\sim90\% UV emission comes from the intensive star formation in the host galaxy.

Keywords

Cite

@article{arxiv.2007.14547,
  title  = {An X-ray Luminosity-dependent "Changing-look" Phenomenon in UGC 3223},
  author = {J. Wang and D. W. Xu and J. Y. Wei},
  journal= {arXiv preprint arXiv:2007.14547},
  year   = {2020}
}

Comments

9 pages, 3 figures and 3 tables, accepted by ApJ

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