Spectral changes and BLR kinematics of eruptive changing-look AGN

Ochmann, M. W.; Kollatschny, W.; Zetzl, M.

doi:10.31577/caosp.2020.50.1.318

Cited by 3 publications

(1 citation statement)

References 13 publications

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“…In 2018, an INTEGRAL detection of NGC 1566 at hard X-rays [67] triggered multiwavelength (MWL) follow-up observations [68][69][70][71], revealing high-amplitude variability. These led to the identification of a new CL event in NGC 1566 [72][73][74].…”

Section: Namementioning

confidence: 99%

Changing-Look Narrow-Line Seyfert 1 Galaxies, their Detection with SVOM, and the Case of NGC 1566

Xu,

Komossa,

Grupe

et al. 2024

Universe

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We discuss applications of the study of the new and barely explored class of changing-look (CL) narrow-line Seyfert 1 (NLS1) galaxies and comment on their detection with the space mission SVOM (Space Variable Objects Monitor). We highlight the case of NGC 1566, which is outstanding in many respects, for instance as one of the nearest known CL AGN undergoing exceptional outbursts. Its NLS1 nature is discussed, and we take it as a nearby prototype for systems that could be discovered and studied in the near future, including with SVOM. Finally, we briefly examine the broader implications and applications of CL events in NLS1 galaxies and show that such systems, once discovered in larger numbers, will greatly advance our understanding of the physics of the environment of rapidly growing supermassive black holes. This White Paper is part of a sequence of publications which explore aspects of our understanding of (CL) NLS1 galaxy physics with future missions.

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Section: Namementioning

confidence: 99%

Changing-Look Narrow-Line Seyfert 1 Galaxies, their Detection with SVOM, and the Case of NGC 1566

Xu,

Komossa,

Grupe

et al. 2024

Universe

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The post-maximum behaviour of the changing-look Seyfert galaxy NGC 1566

Winkler

Tsygankov

Липунов

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present results of the long-term multi-wavelength study of optical, UV and X-ray variability of the nearby changing-look (CL) Seyfert NGC 1566 observed with the Swift Observatory and the MASTER Global Robotic Network from 2007 to 2019. We started spectral observations with South African Astronomical Observatory 1.9-m telescope soon after the brightening was discovered in July 2018 and present here the data for the interval between Aug. 2018 to Sep. 2019. This paper concentrates on the remarkable post-maximum behaviour after July 2018 when all bands decreased with some fluctuations. We observed three significant re-brightenings in the post-maximum period during 17 Nov. 2018–10 Jan. 2019, 29 Apr.–19 Jun. 2019 and 27 Jul.–6 Aug. 2019. An X-ray flux minimum occurred in Mar. 2019. The UV minimum occurred about 3 months later. It was accompanied by a decrease of the Luv/Lx ratio. New post-maximum spectra covering (31 Nov. 2018 – 23 Sep. 2019) show dramatic changes compared to 2 Aug. 2018, with fading of the broad lines and [Fe X] λ6374 until Mar. 2019. These lines became somewhat brighter in Aug.-Sep. 2019. 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 due mostly to fluctuations in the energy generation. The estimated Eddington ratios are about 0.055% for minimum in 2014 and 2.8% for maximum in 2018.

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Broad-band X-ray observations of the 2018 outburst of the changing-look active galactic nucleus NGC 1566

Jana

Kumari

Nandi

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We study the nature of the changing-look Active Galactic Nucleus NGC 1566 during its June 2018 outburst. During the outburst, the X-ray intensity of the source rises up to ∼25–30 times compared to its quiescent state intensity. We perform timing and spectral analysis of the source during pre-outburst, outburst and post-outburst epochs using semi-simultaneous observations with the XMM-Newton, Nuclear Spectroscopic Telescope Array (NuSTAR) and Neil Gehrels Swift Observatories. We calculate variance, normalized variance, and fractional rms amplitude in different energy bands to study the variability. The broad-band 0.5–70 keV spectra are fitted with phenomenological models, as well as physical models. A strong soft X-ray excess is detected in the spectra during the outburst. The soft excess emission is found to be complex and could originate in the warm Comptonizing region in the inner accretion disc. We find that the increase in the accretion rate is responsible for the sudden rise in luminosity. This is supported by the ‘q’-shape of the hardness-intensity diagram that is generally found in outbursting black hole X-ray binaries. From our analysis, we find that NGC 1566 most likely harbours a low-spinning black hole with the spin parameter a* ∼ 0.2. We also discuss a scenario where the central core of NGC 1566 could be a merging supermassive black hole.

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Spectral changes and BLR kinematics of eruptive changing-look AGN

Cited by 3 publications

References 13 publications

Changing-Look Narrow-Line Seyfert 1 Galaxies, their Detection with SVOM, and the Case of NGC 1566

Changing-Look Narrow-Line Seyfert 1 Galaxies, their Detection with SVOM, and the Case of NGC 1566

The post-maximum behaviour of the changing-look Seyfert galaxy NGC 1566

Broad-band X-ray observations of the 2018 outburst of the changing-look active galactic nucleus NGC 1566

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