Year: 2026
Type: preprint
Abstract: We present a systematic interferometric search for close supermassive black hole (SMBH) binaries in 20 nearby type 1 active galactic nuclei (AGN) observed with VLTI/\grav. We investigate parsec-scale asymmetric emission by modeling the squared visibilities and closure phases with a single circular Gaussian component plus a background point source for the central AGN, and searching for additional compact companions through grid-based binary models. The robustness of the search is validated using injection-recovery simulations and point-spread-function diagnostics. Several features are identified in the initial significance maps, but only one candidate out of 20 shows a persistent compact asymmetry, corresponding to an observed incidence of $5\%$. If NGC~3783 is interpreted as a binary AGN, we derive a Poissonian one-sided $1σ$ upper limit of $f_{\rm bin}<16.5\%$ for GRAVITY-detectable binaries among bright nearby AGN (K<12.5) at separations of $\sim1$-$100$~pc. Conversely, if the observed asymmetry in NGC~3783 is associated with asymmetric circumnuclear dust emission, the corresponding upper limit on the binary fraction is $f_{\rm bin}<9.2\%$. We compare these results with predictions from the Horizon-AGN simulation, finding comparable binary fractions. We also noted that the expected fraction strongly depends on the assumed distribution of individual SMBH accretion rates within binaries, which is currently unresolved in cosmological models. Our results demonstrate the potential of infrared interferometry to identify parsec-scale binary AGN candidates and motivate future GRAVITY+ observations to expand the sample and follow up known candidates, helping to confirm their nature and distinguish genuine binaries from asymmetric nuclear structures.
Source: arXiv (Cornell University)
Authors: GRAVITY Collaboration, Dayem, K. Abd El, Aimar, N., Berdeu, A., Berger, J. -P., Bourdarot, G., Brandner, W., Cao, Y., Correia, C., D'Amato, Q., Davies, R., Defrère, D., Drescher, A., Eisenhauer, F., Fabricius, M., Feuchtgruber, H., Flesch, S., Schreiber, N. M. Förster, Foschi, A., Fournier, Q., Garcia, P., Lopez, R. Garcia, Genzel, R., Gillessen, S., Gonté, F., Haubois, X., Hönig, S. F., Ho, L. C., Houllé, M., Joharle, S., Kammerer, J., Kaufer, A., Kervella, P., Kolb, J., Kreidberg, L., Labadie, L., Lacour, S., Lai, O., Laugier, R., Bouquin, J. B. Le, Leftley, J., Li, R., Li, K., Lopez, B., Lutz, D., Mannucci, F., Mang, F., Mérand, A., Millour, F., Montargès, M., Morujão, N., Nowacki, H., Nowak, M., Oberti, S., Osorno, J., Ott, T., Paladini, C., Pappert, S., Paumard, T., Perraut, K., Perrin, G., Petrov, R., Petrucci, P. O., Pourré, N., Rabien, S., Ribeiro, D. C., Robbe-Dubois, S., Bordoni, M. Sadun, Sanchez-Bermudez, J., Sauter, J., Scialpi, M., Scigliuto, J., Shangguan, J., Shimizu, T., Soulez, F., Straubmeier, C., Sturm, E., Subroweit, M., Sykes, C., Tacconi, L. J., Thévenet, P., Urso, I., Vincent, F., Woillez, J., Zins, G.
Institutions: Lagrange Laboratory, École Normale Supérieure de Lyon, Centre National de la Recherche Scientifique, Centre de Recherche Astrophysique de Lyon, University of Chile, European Southern Observatory, University of Southampton, Peking University, University of Cologne, Université Côte d'Azur, Observatoire de la Côte d’Azur, Flatiron Institute, Arcetri Astrophysical Observatory, National Institute for Astrophysics, Universidad Nacional Autónoma de México, Université de Lyon
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: European Commission, Agence Nationale de la Recherche, National Natural Science Foundation of China, Centre National d’Etudes Spatiales, Conseil Régional, Île-de-France, Università degli Studi di Trento, European Southern Observatory, Centre National de la Recherche Scientifique, Universidade de Lisboa, Fundação para a Ciência e a Tecnologia, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, Institut National de Physique Nucléaire et de Physique des Particules, NextGenerationEU
OpenAlex ID: W7221813513