Optical and X-ray discovery of the changing-look AGN IRAS 23226-3843 showing extremely broad and double-peaked Balmer profiles

Kollatschny, W.; Grupe, D.; Parker, M. L.; Ochmann, M. W.; Schartel, N.; Herwig, E.; Komossa, Stefanie; Romero-Colmenero, E.; Santos-Lleo, M.

doi:10.1051/0004-6361/202037897

Cited by 25 publications

(17 citation statements)

References 73 publications

(79 reference statements)

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“…These models might be restricted by the statistical studies after extending the sample of CL-AGNs. Several groups have devoted to searching for new CL-AGNs, and tens candidates have been discovered based on the large optical and X-ray surveys, such as the Sloan Digital Sky Survey (SDSS; e.g., LaMassa et al 2015;MacLeod et al 2016;Rumbaugh et al 2018;Hon et al 2020), intermediate Palomar Transient Factory (iPTF;Gezari et al 2017), Pan-STARRS1 (PS1;MacLeod et al 2019), Catalina Real-time Transient Survey (CRTS; Yang et al 2018), and XMM-Newton slew survey (Zetzl et al 2018;Kollatschny 2020). In the future, the Large Synoptic Survey Telescope (LSST) will regularly monitor millions of AGNs, and the number of CL-AGNs will further increase.…”

Section: Introductionmentioning

confidence: 99%

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

Feng,

Hu,

et al. 2020

Preprint

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The changes of broad emission lines should be a crucial issue to understanding the physical properties of changing-look active galactic nucleus (CL-AGN). Here, we present the results of an intensive and homogeneous 6-month long reverberation mapping (RM) monitoring campaign during a low-activity state of the CL-AGN Seyfert galaxy NGC 3516. Photometric and spectroscopic monitoring was carried out during 2018-2019 with the Lijiang 2.4 m telescope. The sampling is 2 days in most nights, and the average sampling is ∼3 days. The rest frame time lags of Hα and Hβ are τ Hα = 7.56 +4.42 −2.10 days and τ Hβ = 7.50 +2.05 −0.77 days, respectively. From a RMS Hβ line dispersion of σ line = 1713.3 ± 46.7 km s −1 and a virial factor of f σ = 5.5, the central black hole mass of NGC 3516 is estimated to be M BH = 2.4 +0.7 −0.3 × 10 7 M ⊙ , which is in agreement with previous estimates. The velocity-resolved delays show that the time lags increase towards negative velocity for both Hα and Hβ. The velocity-resolved RM of Hα is done for the first time. These RM results are consistent with other observations before the spectral type change, indicating a basically constant BLR structure during the changing-look process. The CL model of changes of accretion rate seems to be favored by long-term Hβ variability and RM observations of NGC 3516.

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Section: Introductionmentioning

confidence: 99%

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

Feng,

Hu,

et al. 2020

Preprint

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“…The latter lack broad Balmer emission lines in their spectra, widely understood by the unified model (e.g., Antonucci 1993) in which its central engine is obscured by the dusty torus along the line of sight to an observer. This orientation-based model has, however, recently been challenged by the rarely discovered "changing-look" (CL) phenomenon, in which some AGNs show a spectral transition between Type 1, intermediate, and Type 2 within a timescale of years to decades (e.g., MacLeod et al 2010MacLeod et al , 2016Shapovalova et al 2010;Shappee et al 2014;LaMassa et al 2015;McElroy et al 2016;Ruan et al 2016;Runnoe et al 2016;Parker et al 2016;Gezari et al 2017;Sheng et al 2017Sheng et al , 2020Stern et al 2018;Yang et al 2018;Wang et al 2018bWang et al , 2019Wang et al , 2020aFrederick et al 2019;Trakhtenbrot et al 2019;Yan et al 2019;Guo et al 2019;Ai et al 2020;Graham et al 2020;Kollatschny et al 2018Kollatschny et al , 2020. The widely accepted standard disk model has also been challenged by the CL phenomenon in terms of the viscosity crisis (e.g., Lawrence 2018, and references therein).…”

Section: Introductionmentioning

confidence: 99%

B3\,0749+460A: A New "Changing-Look" Active Galactic Nucleus Associated with X-ray Spectral Slope Variations

Wang,

Zheng,

et al. 2021

Preprint

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Here we report an identification of B3 0749+460A 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 MaNGA 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 since 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 decreases 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.

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“…In 2015 LaMassa et al discovered the first CL Quasar and since then the number of known CL-AGNs has increased rapidly (e.g. MacLeod et al 2016;McElroy et al 2016;Runnoe et al 2016;Yang et al 2018;Ruan et al 2016;Sheng et al 2017;Kollatschny et al 2018;Guo et al 2019;Wang et al 2019;Graham et al 2019;Kollatschny et al 2020;Graham et al 2020); however, the number is still fewer than a hundred. Although rare, these objects provide valuable constraints for our models of the central engine.…”

Section: Introductionmentioning

confidence: 99%

The Eddington ratio-dependent changing look events in NGC 2992

Guolo,

Ruschel-Dutra,

Grupe

et al. 2021

Preprint

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We present an analysis of historical multi-wavelength emission of the Changing Look (CL) Active Galactic Nucleus (AGN) in NGC 2992, covering epochs ranging from 1978 to 2021, as well as new X-ray and optical spectra. The galaxy presents multiple Seyfert type transitions from type 2 to intermediate-type, losing and regaining its H𝛼 BEL recurrently. In X-rays, the source shows intrinsic variability with the absorption corrected luminosity varying by a factor of ∼ 40. We rule-out tidal disruption events or variable obscuration as causes of the type transitions, and show that the presence and the flux of the broad H𝛼 emission line are directly correlated with the 2-10 keV X-ray luminosity (L 2−10 ): the component disappears at L 2−10 ≤ 2.6 × 10 42 erg cm −2 s −1 , this value translates into an Eddington ratio (𝜆 Edd ) of ∼ 1%. The 𝜆 Edd in which the BEL transitions occur is the same as the critical value at which there should be a state transition between a radiatively inefficient accretion flow (RIAF) and a thin accretion disk, such similarity suggests that the AGN is operating at the threshold mass accretion rate between the two accretion modes. We find a correlation between the narrow Fe K𝛼 flux and 𝜆 Edd , and an anti-correlation between full-width at half maximum of H𝛼 BEL and 𝜆 Edd , in agreement with theoretical predictions. Two possible scenarios for type transitions are compatible with our results: either the dimming of the AGN continuum, which reduces the supply of ionising photons available to excite the gas in the Broad Line Region (BLR), or the fading of the BLR structure itself occurs as the low accretion rate is not able to sustain the required cloud flow rate in a disk-wind BLR model.

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Optical and X-ray discovery of the changing-look AGN IRAS 23226-3843 showing extremely broad and double-peaked Balmer profiles

Cited by 25 publications

References 73 publications

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

B3\,0749+460A: A New "Changing-Look" Active Galactic Nucleus Associated with X-ray Spectral Slope Variations

The Eddington ratio-dependent changing look events in NGC 2992

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