학술논문
Long-term multiwavelength monitoring and reverberation mapping of NGC 2617 during a changing-look event
Document Type
Working Paper
Author
Oknyansky, V. L.; Brotherton, M. S.; Tsygankov, S. S.; Dodin, A. V.; Tatarnikov, A. M.; Du, P.; Bao, D. -W.; Burlak, M. A.; Ikonnikova, N. P.; Lipunov, V. M.; Gorbovskoy, E. S.; Metlov, V. G.; Belinski, A. A.; Shatsky, N. I.; Zheltouhov, S. G.; Maslennikova, N. A.; Wang, J. -M.; Zhai, S.; Fang, F. -N.; Fu, Y. -X.; Bai, H. -R.; Kasper, D.; Huseynov, N. A.; McLane, J. N.; Maithil, J.; Zastrocky, T. E.; Olson, K. A.; Chen, X.; Chelouche, D.; Oknyansky, R. S.; Buckley, D. A. H.; Tyurina, N. V.; Kuznetsov, A. S.; Rebolo, R. L.; Zhao, B. -X.
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Subject
Language
Abstract
We present the results of photometric and spectroscopic monitoring campaigns of the changing look AGN NGC~2617 carried out from 2016 until 2022 and covering the wavelength range from the X-ray to the near-IR. The facilities included the telescopes of the SAI MSU, MASTER Global Robotic Net, the 2.3-m WIRO telescope, Swift, and others. We found significant variability at all wavelengths and, specifically, in the intensities and profiles of the broad Balmer lines. We measured time delays of ~ 6 days (~ 8 days) in the responses of the H-beta (H-alpha) line to continuum variations. We found the X-ray variations to correlate well with the UV and optical (with a small time delay of a few days for longer wavelengths). The K-band lagged the B band by 14 +- 4 days during the last 3 seasons, which is significantly shorter than the delays reported previously by the 2016 and 2017--2019 campaigns. Near-IR variability arises from two different emission regions: the outer part of the accretion disc and a more distant dust component. The HK-band variability is governed primarily by dust. The Balmer decrement of the broad-line components is inversely correlated with the UV flux. The change of the object's type, from Sy1 to Sy1.8, was recorded over a period of ~ 8 years. We interpret these changes as a combination of two factors: changes in the accretion rate and dust recovery along the line of sight.
Comment: 14 pages, 15 figures, accepted by the MNRAS
Comment: 14 pages, 15 figures, accepted by the MNRAS