NGC 6240: A triple nucleus system in the advanced or final state of merging

Kollatschny, W.; Weilbacher, Peter M.; Ochmann, M. W.; Chelouche, Doron; Monreal-Ibero, A.; Bacon, Roland; Contini, T.

doi:10.1051/0004-6361/201936540

Cited by 60 publications

(57 citation statements)

References 59 publications

(68 reference statements)

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“…The nuclei are at ∼ 1 kpc separation and are likely both Compton thick (i.e., with absorption column density along the line of sight N H > ∼ 10 24 cm −2 ). Recently, Kollatschny et al (2019), using VLT/MUSE data at a resolution of 75 milliarcsec, have reported the discovery of a third nucleus in this galaxy: the Southern component appears to host two distinct nuclei, separated by 198 pc only. The lack of a radio counterpart for the newly detected nucleus suggests that it could be not active; furthermore, no 12 CO(2-1) emission at its position is detected by ALMA (Treister et al, 2020), in stark contrast with the two previously known nuclei.…”

Section: Discovery and Follow-up Observations Of Dual Agnmentioning

confidence: 99%

The quest for dual and binary supermassive black holes: A multi-messenger view

Rosa

Vignali

Bogdanović

et al. 2019

New Astronomy Reviews

201

123

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The quest for binary and dual supermassive black holes (SMBHs) at the dawn of the multi-messenger era is compelling. Detecting dual active galactic nuclei (AGN)-active SMBHs at projected separations larger than several parsecs-and binary AGN-probing the scale where SMBHs are bound in a Keplerian binary-is an observational challenge. The study of AGN pairs (either dual or binary) also represents an overarching theoretical problem in cosmology and astrophysics. The AGN triggering calls for detailed knowledge of the hydrodynamical conditions of gas in the imminent surroundings of the SMBHs and, at the same time, their duality calls for detailed knowledge on how galaxies assemble through major and minor mergers and grow fed by matter along the filaments of the cosmic web. This review describes the techniques used across the electromagnetic spectrum to detect dual and binary AGN candidates and proposes new avenues for their search. The current observational status is compared with the state-of-the-art numerical simulations and models for formation of dual and binary AGN. Binary SMBHs are among the loudest sources of gravitational waves (GWs) in the Universe. The search for a background of GWs at nHz frequencies from inspiralling SMBHs at low redshifts, and the direct detection of signals from their coalescence by the Laser Interferometer Space Antenna in the next decade, make this a theme of major interest for multi-messenger astrophysics. This review discusses the future facilities and observational strategies that are likely to significantly advance this fascinating field.

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Section: Discovery and Follow-up Observations Of Dual Agnmentioning

confidence: 99%

The quest for dual and binary supermassive black holes: A multi-messenger view

Rosa

Vignali

Bogdanović

et al. 2019

New Astronomy Reviews

201

123

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“…Assuming a Hubble constant of H 0 = 68 km s −1 Mpc −1 (Planck Collaboration et al 2014) at the distance of NGC 6240 1 ′′ corresponds to 500 pc, respectively the cores settle on 750 pc. Kollatschny et al (2020) reported a third minor component S2 which placed at 0.42 ′′ (210 pc) from S1 (previous S) nuclei. Below for marking south nu-cleus we will use label S (S1+S2) if we talk about binary system or S1/S2 if we talk about triple system.…”

Section: Ngc 6240 Physical Characteristicsmentioning

confidence: 89%

Merging timescale for supermassive black hole binary in interacting galaxy NGC 6240

Sobolenko,

Berczik,

Spurzem

2021

Preprint

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Context. One of the main possible way of creating the supermassive black hole (SMBH) is a so call hierarchical merging scenario. Central SMBHs at the final phase of interacting and coalescing host-galaxies are observed as SMBH binary (SMBHB) candidates at different separations from hundreds of pc to mpc. Aims. Today one of the strongest SMBHB candidate is a ULIRG galaxy NGC 6240 which was X-ray spatially and spectroscopically resolved by Chandra. Dynamical calculation of central SMBHBs merging in a dense stellar environment allows us to retrace their evolution from kpc to mpc scales. The main goal of our dynamical modeling was to reach the final, gravitational wave (GW) emission regime for the model BHs. Methods. We present the direct N-body simulations with up to one million particles and relativistic post-Newtonian corrections for the SMBHs particles up to 3.5 post-Newtonian terms. Results. Generally speaking, the set of initial physical conditions can strongly effect of our merging time estimations. But in a range of our parameters, we did not find any strong correlation between merging time and BHs mass or BH to bulge mass ratios. Varying the model numerical parameters (such as particle number -N) makes our results quite robust and physically more motivated. From our 20 models we found the upper limit of merging time for central SMBHB is less than ∼55 Myr. This concrete number are valid only for our set of combination of initial mass ratios. Conclusions. Further detailed research of rare dual/multiple BHs in dense stellar environment (based on observations data) can clarify the dynamical co-evolution of central BHs and their host-galaxies.

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“…With its 27 Mpc in distance, NGC 7727 is the dual SMBH system closest to us. Before this work, the closest known dual SMBH was NGC 6240 (Komossa et al 2003;Kollatschny et al 2020), which at 144 Mpc is almost six times as far away from us as NGC 7727. In NGC 6240, similar MUSE data were used to study the system, but only the nuclear components could be spatially separated from each other.…”

Section: The Nearest and Closest Dynamically Confirmed Dual Smbh Systemmentioning

confidence: 99%

“…The closest known dual SMBH is NGC6240 (Komossa et al 2003;Kollatschny et al 2020), which is located at 144 Mpc. In the study of NGC 6240 by Kollatschny et al (2020), based on MUSE observations, a spatial resolution was reached that is good enough to show that the emission lines come from two separate stellar components and are thus a true dual SMBH. They discovered that it might be a triple AGN system with three accreting black holes within a separation of ∼1 kpc.…”

Section: Introductionmentioning

confidence: 99%

First direct dynamical detection of a dual supermassive black hole system at sub-kiloparsec separation

Voggel

Seth

Baumgardt

et al. 2022

A&A

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We investigated whether the two recently discovered nuclei in NGC 7727 both host a super-massive black hole (SMBH). We used the high spatial resolution mode of the integral-field spectrograph MUSE on the VLT in adaptive optics mode to resolve the stellar kinematics within the sphere of influence of both putative black holes. We combined the kinematic data with an HST-based mass model and used Jeans models to measure their SMBH mass. We report the discovery of a dual SMBH system in NGC 7727. We detect a SMBH in the photometric center of the galaxy in Nucleus 1, with a mass of M SMBH = 1.54 +0.18 −0.15 × 10 8 M . In the second nucleus, which is 500 pc offset from the main nucleus, we also find a clear signal for a SMBH with a mass of M BH = 6.33 +3.32 −1.40 × 10 6 M . Both SMBHs are detected at high significance. The off-axis nature of Nucleus 2 makes modeling the system challenging; however, a number of robustness tests suggest that a black hole is required to explain the observed kinematics. The SMBH in the offset Nucleus 2 makes up 3.0% of its total mass, which means its SMBH is over-massive compared to the M BH − M Bulge scaling relation. This confirms it as the surviving nuclear star cluster of a galaxy that has merged with NGC 7727. This discovery is the first dynamically confirmed dual SMBH system with a projected separation of less than a kiloparsec and the nearest dynamically confirmed dual SMBH at a distance of 27.4 Mpc. The second Nucleus is in an advanced state of inspiral, and it will eventually result in a 1:24 mass ratio SMBH merger. Optical emission lines suggest Nucleus 2 is a Seyfert galaxy, making it a low-luminosity Active Galactic Nuclei (AGN). There are likely many more quiescent SMBHs as well as dual SMBH pairs in the local Universe that have been missed by surveys that focus on bright accretion signatures.

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NGC 6240: A triple nucleus system in the advanced or final state of merging

Cited by 60 publications

References 59 publications

The quest for dual and binary supermassive black holes: A multi-messenger view

The quest for dual and binary supermassive black holes: A multi-messenger view

Merging timescale for supermassive black hole binary in interacting galaxy NGC 6240

First direct dynamical detection of a dual supermassive black hole system at sub-kiloparsec separation

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