The outburst of the changing-look AGN IRAS 23226-3843 in 2019

Kollatschny, W.; Grupe, D.; Parker, M. L.; Ochmann, M. W.; Schartel, N.; Romero-Colmenero, E.; Winkler, Hartmut; Komossa, S.; Famula, P.; Probst, M.; Santos-Lleó, M.

doi:10.1051/0004-6361/202244786

Cited by 7 publications

(9 citation statements)

References 100 publications

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“…± 10. km s −1 of the stars in the bulge of NGC 1566 17,18 . We confirm this total central black hole mass of 5 × 10 6 M ⊙ based on CaII triplet observations in NGC 1566 19 .…”

supporting

confidence: 85%

“…Further Swift observations 22 from July 10, 17, 24, and 31 verified the high X-ray and UV flux states, but indicated a decrease with respect to the observation taken on July 10. Follow-up observations in the X-ray with Swift and XMM 23 as well as in the optical 24,25,19 also confirm a decline in the optical, UV and X-ray emission over the following two years and in late 2023 NGC 1566 is still found in a low state in all Swift bands 26 The general shape of the outburst light curve looks surprisingly symmetrical with respect to its highest flux peak in mid 2018 -with additional smaller peaks superimposed on either wing.…”

mentioning

confidence: 68%

“…We tested that the intensity of the forbidden lines from the narrow line region did not change during the lensing event, and therefore that the narrow line region was not lensed: For this test, we compared the combined ASAS-SN V-band and g-band light curve with a V-band continuum light curve extracted from the intercalibrated spectroscopic data in Ochmann 19 . The spectroscopic data had previously been intercalibrated according to the flux intensity of the narrow lines.…”

Section: Competing Interestsmentioning

confidence: 99%

“…The mass of the lens can be estimated if reasonable assumptions can be made for the distances and transverse velocities. The intensity of the [OIII] λ 5007 emission remained constant 25,19 throughout the A nearly edge-on binary orientation is necessary to produce self-lensing systems of MBHB, i.e.…”

mentioning

confidence: 99%

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Gravitational self-lensing of the supermassive black hole binary in NGC1566

Kollatschny,

Probst,

Ochmann

et al. 2023

Preprint

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It is generally accepted that all massive galaxies host supermassive black holes in their center1 and that mergers of two galaxies lead to the formation of black hole binaries2. The most interesting among them comprise the mergers in their final state, i.e. with pc (3.2 light years) or sub-pc orbital separations. Binary self-lensing is a possibility to detect these systems. Here we report the detection of a central supermassive black hole binary in the active galaxy (AGN) NGC1566 based on a microlensing outburst. The light curve of the outburst - based on observations with the All Sky Automated Survey for SuperNovae - lasted from the beginning of the year 2017 until the beginning of 2020. The shape of the symmetric light curve looks very different with respect to normal random variations of AGN3,4. However, it could be easily reproduced with a best-fit standard microlensing light curve5. Based on the light curve we derive a characteristic time-scale of 155 days. During the outburst, the continuum as well as the broad line intensities varied - however the narrow emission lines did not. This is an indication that the lensing object orbits the AGN nucleus between the broad line region and the narrow line region, i.e. at a distance on the order of 250 light days. The observed characteristic time-scale depends on the lens mass, the distances between lens and source, and the transverse velocity. The light curve can be reproduced by a lens with a black hole (BH) mass of 5x105 M⊙. This implies a mass ratio to the central AGN on the order of 1 to 10.

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“…± 10. km s −1 of the stars in the bulge of NGC 1566 17,18 . We confirm this total central black hole mass of 5 × 10 6 M ⊙ based on CaII triplet observations in NGC 1566 19 .…”

supporting

confidence: 85%

mentioning

confidence: 68%

Section: Competing Interestsmentioning

confidence: 99%

mentioning

confidence: 99%

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Gravitational self-lensing of the supermassive black hole binary in NGC1566

Kollatschny,

Probst,

Ochmann

et al. 2023

Preprint

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“…The optical spectrum of this AGN has an asymmetric broad H α emission line as well as a broad double-peaked H β emission line. In addition, the source also has narrow emission lines like Kollatschny et al (2023) reported that the optical continuum and the Balmer line intensities showed drastic differences when the spectra were compared between the years 1999 and 2017. The double-peaked emission line is from the underlying accretion disk in this source.…”

Section: A Changing-look Agnmentioning

confidence: 98%

A Relook at the Black Hole Binary Candidate J1328+2752 with VLBI

Nandi,

Kharb,

Caproni

et al. 2024

ApJ

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We present multiband follow-up observations of the supermassive binary black hole (BBH) candidate and misaligned double–double radio galaxy, J1328+2752. To investigate its parsec-scale structure, we have carried out observations with the Very Long Baseline Array (VLBA) and the European Very Long Baseline Interferometry (VLBI) Network. Additionally, we have obtained optical spectroscopic observations with the 3.6 m Devasthal Optical Telescope. Within 3.5 yr of our previous VLBI observations, the central parsec-scale radio structure of J1328+2752 has changed from a double component to a single central component and its flux density has increased by a factor of 3 in the 5 GHz VLBA observations. The new radio component is largely unresolved at 3, 5, and 8 GHz. The multifrequency radio data shows a convex-shaped spectrum for this unresolved component. The turnover frequency is at ∼3 GHz. While the total intensity image does not reveal any details, a super-resolved VLBA 5 and 8 GHz spectral index image does indicate the presence of two components at a separation of ∼4.2 pc with spectral indices −0.5 ± 0.3 and −0.9 ± 0.3. We have not observed a simultaneous change in the optical line profiles or intensities over the past few years. The radio structure, the variation of the flux density, and spectral shape can potentially be consistent both with the signature of a young radio source or a BBH at the center of J1328+2752.

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Long-term optical spectral monitoring of a changing-look active galactic nucleus NGC 3516

Ilić¹,

Burenkov²,

Álvarez³

2023

A&A

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Context. We analyze the broad Hβ line profile variability of a “changing look” active galactic nucleus (CL-AGN) NGC 3516 over an extensive period of 25 years (from 1996 to 2021). The observed change in the broad line profile may indicate a change in the geometry of the broad line region (BLR). The main objective is to follow and understand the change in the BLR over a long period as well as its connection to the CL mechanism. Aims. Using spectral line profiles, we aim to explore changes in the kinematics and dimensions of the BLR in NGC 3516. We consider two possible scenarios: the changes in the broad-line emission are either caused by a decrease of ionisation continuum emission or by the BLR obscuration by outer dusty regions. With this investigation, we aim to clarify the CL mechanism of this AGN. Methods. We analyzed the spectral band around the Hβ line as well as the broad Hβ line parameters and how they change over time. We modelled the broad-line profiles, assuming that there is an emission from the accretion disc superposed with emission from a surrounding region that is outside the disc. Results. We find that in the type 1 activity phase occurring when the strong broad emission lines are observed, the BLR is very complex. There is a clear disc-like BLR that contributes to the broad line wings and an additional intermediate line region (ILR) that contributes to the line core. In the high-activity phase, the ILR emission is close to the center of the line, although in some cases, it is slightly shifted to the red. In the low-activity phase (i.e. type 2 phase), the ILR component has a significant shift to the blue, indicating an outflow. Conclusions. We propose that the changing-look mechanism in NGC 3516 is rather connected with the intrinsic effects than with an outer obscuring region. It may still be possible that the dust plays an important role in the low-activity phase when it is coming from within the BLR, leading to a dusty BLR. In this way, it would cause a decrease in the ionisation and recombination rates.

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The outburst of the changing-look AGN IRAS 23226-3843 in 2019

Cited by 7 publications

References 100 publications

Gravitational self-lensing of the supermassive black hole binary in NGC1566

Gravitational self-lensing of the supermassive black hole binary in NGC1566

A Relook at the Black Hole Binary Candidate J1328+2752 with VLBI

Long-term optical spectral monitoring of a changing-look active galactic nucleus NGC 3516

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