Swift observations of the changing-look AGN UGC 3223: X-ray low-state and extended UV emission

ATel #13798; J. Wang (Guangxi University; National Astronomical Observatories, Chinese Academy of Sciences), S. Komossa (MPIfR), D. W. Xu (National Astronomical Observatories, Chinese Academy of Sciences; School of Astronomy and Space Science, University of Chinese Academy of Sciences), J. Y. Wei (National Astronomical Observatories, Chinese Academy of Sciences; School of Astronomy and Space Science, University of Chinese Academy of Sciences)
on 10 Jun 2020; 12:14 UT
Credential Certification: St. Komossa (stefanie.komossa@gmx.de)

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We report on Neil Gehrels Swift observations of the Seyfert galaxy UGC 3223, which was recently identified as a changing-look AGN changing type between Sy 1.5, Sy 2.0 and Sy 1.8 over 32 yr (Wang et al. 2020, AJ 159, 245). We observed UGC 3223 three times with Swift on 2020 March 31, April 6 and April 10 in the UV filters and in X-rays. UGC 3223 turns out to be in an X-ray low-state, with (0.3-10 keV) XRT countrates of 4.77(+/-0.75)e-2, 4.51(+/-1.37)e-2, 5.14(+/-0.80)e-2 cts/s, respectively. A joint spectral fit to the 3 data sets with a simple model of a single powerlaw with Galactic absorption gives an unusually flat photon index Gamma_x ~ 0.8 +- 0.3, which very likely implies the presence of strong excess absorption and a steeper intrinsic powerlaw, or else a significant starburst contribution. The latter is unlikely, since the simple powerlaw approximation implies an intrinsic (0.3-10 keV)luminosity on the order of 10^42 erg/s. When compared to previous X-ray observations of UGC 3223, taken with ROSAT (in the 1990s) and Swift (in 2013 and 2014), we find that the X-ray brightness follows the Seyfert state of UGC 3223, in the sense that X-rays are brighter if the source is seen closer to type 1. With ROSAT, UGC3223 was in its highest X-ray state. The Swift UVOT UV images of UGC 3223 reveal the presence of extended emission in form of a ring-like structure with an extent of 30 arcsec. Its appearance is most likely caused by a dust lane in the host galaxy (Deo et al. 2006, AJ 132, 321). The total UV emission is constant when compared to the GALEX NUV observation in 2013 (Bai et al. 2015, ApJ 220, 6).