B3 0749+460A: A New Repeat “Changing-look” Active Galactic Nucleus Associated with X-Ray Spectral Slope Variations  

作　　者：J.Wang W.K.Zheng D.W.Xu T.G.Brink A.V.Filippenko C.Gao S.S.Sun J.Y.Wei 

机构地区：[1]Guangxi Key Laboratory for Relativistic Astrophysics,School of Physical Science and Technology,Guangxi University,Nanning 530004,China [2]Key Laboratory of Space Astronomy and Technology,National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China [3]Department of Astronomy,University of California,Berkeley,CA 94720-3411,USA [4]School of Astronomy and Space Science,University of Chinese Academy of Sciences,Beijing 100049,China [5]Miller Institute for Basic Research in Science,University of California,Berkeley,CA 94720,USA

出　　处：《Research in Astronomy and Astrophysics》2022年第1期114-125,共12页天文和天体物理学研究（英文版）

基　　金：support from the National Key Research and Development Project of China (grant 2020YFE0202100);supported by the National Natural Science Foundation of China (Grants No.11773036 and 12173009);Strategic Pioneer Program on Space Science;Chinese Academy of Sciences,grants XDA15052600 and XDA15016500;supported by the Natural Science Foundation of Guangxi(2020GXNSFDA238018);the Bagui Young Scholars Program;supported by the Open Project Program of the Key Laboratory of Optical Astronomy,NAOC,CAS;supported by the Christopher R.Redlich Fund and the Miller Institute for Basic Research in Science (in which A.V.F.is a Senior Miller Fellow) funded by the National Aeronautics and Space Administration (NASA);partially supported by a generous gift from Google。

摘　　要：Here we report an identification of B3 0749+460 A as a new double-peaked local "changing-look" active galactic nucleus(CL-AGN) in terms of our multi-epoch spectroscopic analysis. By comparing our new spectra taken in 2021 with the ones taken by the Sloan Digital Sky Survey in 2004, BOSS in 2013 and Ma NGA in 2016, we reveal type transitions of Seyfert(Sy) 1.9 → Sy1.8 → Sy1.9. In the transitions, the classical broad Hα emission fades away after 2013 and disappears in our 2021 spectrum, although the absence of broad Hβ can be traced back to at least 2016. A follow-up observation in X-rays by the Swift/XRT reveals that(1) the X-ray emission level gradually decreased since 2005;and(2)the X-ray spectrum is soft in the optical "turn-off" state and hard in the "turn-on" state. We argue that the disappearance of the classical broad Hα emission can be likely explained by the disk-wind broad-line-region model, in which the CL phenomenon is sensitive to luminosity in individual AGNs.

关 键 词：galaxies:Seyfert galaxies:nuclei (galaxies:)quasars:emission lines (galaxies:)quasars:individual(B30749+460A) X-rays:galaxies 

分 类 号：P157.6[天文地球—天文学]