A possible sub-kiloparsec dual AGN buried behind the galaxy curtain

Abstract

Although thousands of galaxy mergers are known, only a handful of sub-kiloparsec-scale supermassive black hole (SMBH) pairs have been confirmed so far, leaving a huge gap between the observed and predicted numbers of such objects. In this work, we present a detailed analysis of the Sloan Digital Sky Survey optical spectrum and of near-infrared (NIR) diffraction limited imaging of SDSS~J1431+4358. This object is a local radio-quiet type 2 active galactic nucleus (AGN) previously selected as a double AGN candidate on the basis of the double-peaked [OIII] emission line. The NIR adaptive optics-assisted observations were obtained at the Large Binocular Telescope with the LUCI+FLAO camera. We found that most of the prominent optical emission lines are characterized by a double-peaked profile, mainly produced by AGN photoionization. Our spectroscopical analysis disfavors the hypothesis that the double-peaked emission lines in the source are the signatures of outflow kinematics, leaving open the possibility that we are detecting either the rotation of a single narrow-line region or the presence of two SMBHs orbiting around a common central potential. The latter scenario is further supported by the high-spatial resolution NIR imaging: after subtracting the dominant contribution of the stellar bulge component in the host galaxy, we detect two faint nuclear sources at r<0.5 kpc projected separation. Interestingly, the two sources have a position angle consistent with that defined by the two regions where the [OIII] double peaks most likely originate. Aside from the discovery of a promising sub-kiloparsec scale dual AGN, our analysis shows the importance of an appropriate host galaxy subtraction in order to achieve a reliable estimate of the incidence of dual AGNs at small projected separations.

11 pages, 8 figures, 1 table, accepted by A&A (revised to match the A&A version)

References in corpus (23)

• The Host Galaxies and Classification of Active Galactic Nuclei
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• An Observational Determination of the Bolometric Quasar Luminosity Function
• An online repository of Swift/XRT light curves of GRBs
• Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
• Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
• Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population
• A Compact Supermassive Binary Black Hole System
• A massive binary black-hole system in OJ287 and a test of general relativity
• A possible close supermassive black-hole binary in a quasar with optical periodicity
• On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies
• Formation of z ~ 6 quasars from hierarchical galaxy mergers
• A Candidate Sub-Parsec Supermassive Binary Black Hole System
• Massive binary black holes in galactic nuclei and their path to coalescence
• Active Galactic Nucleus Pairs from the Sloan Digital Sky Survey. I. The Frequency on ~ 5-100 kpc Scales
• A close-pair binary in a distant triple supermassive black-hole system
• A candidate sub-parsec binary black hole in the Seyfert galaxy NGC 7674
• Shocks and angular momentum flips: a different path to feeding the nuclear regions of merging galaxies
• Radio-Selected Binary Active Galactic Nuclei from the Very Large Array Stripe 82 Survey
• Searching for Binary Supermassive Black Holes via Variable Broad Emission Line Shifts: Low Binary Fraction
• The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei II: Kinematic Classifications for the Population at z < 0.1
• Evidence from the Very Long Baseline Array that J1502SE/SW are Double Hotspots, not a Supermassive Binary Black Hole
• Color-magnitude relations of late-type galaxies

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• Periodic variability of the z=2.0 quasar QSO B1312+7837
• Variations of Broad Emission Lines from periodicity QSOs under the interpretation of supermassive binary black holes with misaligned circumbinary broad line regions
• Fast, dust-poor outflows in the local candidate dual AGN MCG-03-34-64 observed with VLT/ERIS
• SDSS J153231.80+420342.7: a triple black hole candidate with a close binary black hole
• A Population Study for Searching Supermassive Binary Black Holes in Active Galactic Nuclei: Continuum Spectral Features and Periodic Variabilities