The changing-look AGN SDSS J101152.98+544206.4 is returning to a type I state
Bing Lyu, Xue-Bing Wu, Yuxuan Pang, Huimei Wang, Rui Zhu, Yuming Fu, Qingwen Wu, Zhen Yan, Wenfei Yu, Hao Liu, S. J. Kang, Junjie Jin, Jinyi Yang, Feige Wang
Abstract
Aims. We discovered that the changing-look active galactic nucleus (CLAGN) SDSS J101152.98+544206.4 (J1011+5442 for short) gradually returns to the type I state after a short period between 2014 and 2019 in the faint type 1.9 state. Methods. Motivated by the rebrightening in the optical and mid-infrared light curves from ZTF and WISE, we obtained new spectroscopic observations with the Xinglong 2.16 m, the Lijiang 2.4 m, and the MMT 6.5 m optical telescopes in 2024. Results. After changing its optical AGN type from 1 to 1.9 between 2003 and 2015 according to the repeat spectroscopy from the Time Domain Spectroscopic Survey, J1011+5442 returned to its type I state in 2024. We detect the significant and very broad H β lines (full width at half maximum of ≳5000 km/s) based on the new spectra, which suggests that J1011+5442 was in the intermediate state between the dim state in 2015 and the bright state in 2003. The long-term optical and mid-infrared light curves also show a brightening trend between 2019 and 2024 as the broad H β line appeared. The time lag of about 100 days between the mid-infrared and optical variability is consistent with the prediction of dust reverberation mapping. Conclusions. The behavior of the photometric and spectroscopic observations of J1011+5442 is consistent with the argument that the repeating changing-look phenomenon is regulated by the variation in the accretion rate.