Changing looks of the nucleus of the Seyfert galaxy NGC 1566 compared with other changing-look AGNs
arXiv:2111.02818 · doi:10.1002/asna.20210080
Abstract
We present results of a long-term optical, UV and X-ray study of variability of the nearby changing-look (CL) Seyfert NGC 1566 which was observed with the Swift Observatory from 2007 to 2020. We summarize our previously published spectroscopic and photometric results and present new observations. We reported on the alteration in the spectral type of NGC 1566 in 2018 (REF1). Moreover, we focused on the exceptional postmaximum behavior after 2018 July, when all bands dropped with some fluctuations (REF2). We observed four significant re-brightenings in the post-maximum period. We have found differences in X-ray and UV/Optical variability. The L_uv/L_x-ray ratio was decreased during 2018-2020. New post-maximum spectra covering the period 2018 November 31 to 2019 September 23 show dramatic changes compared to 2018 August 2, with fading of the broad lines and [Fe X] 6374 until 2019 March (REF2). Effectively, two CL states were observed for this object: changing to type 1.2 and then returning to the low state as a type 1.8 Sy. We suggest that the changes are mostly due to fluctuations in the energy generation. Variability properties of NGC1566 are compared with our results for other CL AGNs.
arXiv comment7 pages, 2 figures, accepted by AstronNachr. arXiv admin note: substantial text overlap with arXiv:2006.00001
References in corpus (29)
- The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
- The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
- Changing-Look Quasar Candidates: First Results from Follow-up Spectroscopy of Highly Optically Variable Quasars
- Swift monitoring of NGC 5548: X-ray reprocessing and short term UV/optical variability
- Swift monitoring of NGC 4151: Evidence for a Second X-ray/UV Reprocessing
- Mid-infrared variability of changing-look AGN
- Long term optical and X-ray variability of the Seyfert galaxy Markarian 79
- Long-term variability of the optical spectra of NGC 4151: II. Evolution of the broad Ha and Hb emission-line profiles
- New changing look case in NGC 1566
- Long-term variability of the optical spectra of NGC 4151: I. Light curves and flux correlations
- The case for cases B and C: intrinsic hydrogen line ratios of the broad-line region of active galactic nuclei, reddenings, and accretion disc sizes
- Ultraviolet and X-ray variability of active galactic nuclei with Swift
- Profile variability of the H-alpha and H-beta broad emission lines in NGC5548
- Multiple tidal disruption flares in the active galaxy IC 3599
- Evidence for a receding dust sublimation region around a supermassive black hole
- Relativistic cross sections of mass stripping and tidal disruption of a star by a super-massive rotating black hole
- Broad Band X-Ray Spectra of Two Low-luminosity Active Galactic Nuclei NGC 1566 and NGC 4941
- NGC 1566: analysis of the nuclear region from optical and near-infrared Integral Field Unit spectroscopy
- Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516
- The curtain remains open: NGC 2617 continues in a high state
- The analysis of the hydrogen broad Balmer line ratios: possible implications to the physical properties of the BLR of AGN
- Broadband X-Ray Observations of the 2018 Outburst of the Changing-Look Active Galactic Nucleus NGC 1566
- The post-maximum behaviour of the changing-look Seyfert galaxy NGC 1566
- The relationship between X-ray and optical absorbers in active galactic nuclei
- Mechanism of the Changing Look phenomenon in Active Galactic Nuclei
- Tracing the AGN/X-ray Binary Analogy with Light Curves of Individual Changing-Look AGN
- The Large Amplitude X-ray Variability in NGC 7589: Possible Evidence for Accretion Mode Transition
- The Relative Wavelength Independence of IR Time Lags in NGC4151 During the Years 2010-2015
- Changing looks of the nucleus of the Seyfert galaxy NGC 1566 compared with other changing-look AGNs