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تسجيل مستخدم جديدAn X-ray Luminosity-dependent Changing-look Phenomenon in UGC 3223
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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 $mathrm{S1.5rightarrow S2 rightarrow S1.8}$ 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 $sim2times10^{-4}$ 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.
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Changing-look phenomenon observed now in a growing number of active galaxies challenges our understanding of the accretion process close to a black hole. We propose a simple explanation for periodic outbursts in sources operating at a few per cent of
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We analyze the X-ray, optical, and mid-infrared data of a changing-look Seyfert galaxy sdssj15 at $zsimeq0.086$. Over a period of one decade (2009 - 2018), its broad H$alpha$ line intensity increased by a factor of $sim$4. Meanwhile, the X-ray emissi
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Two major challenges to unification schemes for active galactic nuclei (AGN) are the existence of Narrow-Line Seyfert 1s (NLS1s) and the existence of changing-look (CL) AGNs. AGNs can drastically change their spectral appearance in the optical (chang
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