X-Ray Spectral Shape Variation in Changing-look Seyfert Galaxy SDSS J155258+273728

Ai, Yong; Dou, Liming; Yang, Chenwei; Sun, Luming; Xie, Fu-Guo; Yao, Shujie; Wu, Xue-Bing; Wang, Tinggui; Shu, Xinwen; Jiang, Ning

doi:10.3847/2041-8213/ab7306

Cited by 39 publications

(30 citation statements)

References 88 publications

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“…A change of R tr may generate a transition in the accretion regime. Ai et al (2020) find the similarity in the X-ray spectral evolution between CL-AGNs and black hole X-ray binaries, which implies that the observed CL-AGN phenomena may be related to the state transition in accretion physics. The hard X-ray emission from NGC 3516 (e.g., Ilić et al 2020) −0.12 on 2009 October 28 (Noda et al 2016).…”

Section: Discussionmentioning

confidence: 67%

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: Discussionmentioning

confidence: 67%

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

Feng,

Hu,

et al. 2020

Preprint

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“…The appearance of the blue bump implies an increase of accretion rate of the black hole, and consequently the BELs become stronger due to photoionization. The similarity in the X-ray spectral evolution between CL-AGNs and black hole X-ray binaries indicates that the observed CL-AGN phenomena may be related to the state transition in accretion physics (Ai et al 2020). The latest research shows that X-ray variability observed in CL-AGNs is produced by changes of accretion disk structure and accretion rate (Igarashi et al 2020).…”

Section: Discussionmentioning

confidence: 93%

Velocity-resolved Reverberation Mapping of Changing-look AGN NGC 2617

Feng,

Liu,

Bai

et al. 2021

Preprint

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NGC 2617 has attracted a lot of attention after the detection of the changes in spectral type, and its geometry and kinematics of broad-line region (BLR) are still ambiguous. In this paper, we present the high cadence (∼ 2 days) reverberation mapping campaign of NGC 2617 from 2019 October to 2020 May undertaken at Lijiang 2.4 m telescope. For the first time, the velocity-resolved reverberation signature of the object was successfully detected. Both Hα and Hβ show an asymmetrical profile with a peak in the velocity-resolved time lags. For each of both lines, the lag of the line core is longer than those of the relevant wings, and the peak of the velocity-resolved lags is slightly blueshifted. These characteristics are not consistent with the theoretical prediction of the inflow, outflow or Keplerian disk model. Our observations give the time lags of Hα, Hβ, Hγ, and He i, with a ratio of τ Hα :τ Hβ :τ Hγ :τ He I = 1.27:1.00:0.89:0.20, which indicates a stratified structure in the BLR of the object. It is the first time that the lags of Hα and He i are obtained. Assuming a virial factor of f = 5.5 for dispersion width of line, the masses of black hole derived from Hα and Hβ are 23.8 +5.4 −2.7 and 21.1 +3.8 −4.4 × 10 6 M ⊙ , respectively. Our observed results indicate the complexity of the BLR of NGC 2617.

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“…Inspired by changes in the accretion states of X-ray binaries, Noda & Done (2018) showed that evaporation of the inner part of the disk drives a change in accretion states into a drop, which causes the CL of Mrk 1018. This appears to be supported by the analogy of CL-AGNs to X-ray binaries (Ruan et al 2019;Ai et al 2020;Liu et al 2019). Cooling fronts driven by a sudden change in the magnetic torque at the innermost stable circular orbit (Ross et al 2018), or magnetic fields supporting a geometrically thick disk (Dexter & Begelman 2019), or the radiation pressure instability (Sniegowska et al 2020) lead to a changing state.…”

Section: Introductionmentioning

confidence: 85%

Changing-look active galactic nuclei: close binaries of supermassive black holes in action

Wang

Bon

2020

A&A

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Changing-look active galactic nuclei (CL-AGNs) as a new subpopulation challenge some fundamental physics of AGNs because the timescales of the phenomenon can hardly be reconciled with accretion disk models. In this Letter, we demonstrate the extreme case: close binaries of supermassive black holes (CB-SMBHs) with high eccentricities are able to trigger the CL transition through one orbit. In this scenario, binary black holes build up their own mini-disks by peeling gas off the inner edges of the circumbinary disk during the apastron phase, after which they tidally interact with the disks during the periastron phase to efficiently exchange angular momentum within one orbital period. For mini-disks rotating retrograde to the orbit, the tidal torque rapidly squeezes the tidal parts of the mini-disks into a much smaller radius, which rapidly results in higher accretion and short flares before the disks decline into type-2 AGNs. Prograde-rotation mini-disks gain angular momentum from the binary and rotate outward, which causes a rapid turn-off from type-1 to type-2. Turn-on occurs around the apastron phase. CB-SMBHs control cycle transitions between type-1 and type-2 with orbital periods but allow diverse properties in CL-AGN light curves.

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X-Ray Spectral Shape Variation in Changing-look Seyfert Galaxy SDSS J155258+273728

Cited by 39 publications

References 88 publications

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516

Velocity-resolved Reverberation Mapping of Changing-look AGN NGC 2617

Changing-look active galactic nuclei: close binaries of supermassive black holes in action

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