Searching for Nearby Supermassive Black Hole Binaries with GRAVITY

@misc{collaboration2026searching,
  title = {{Searching for Nearby Supermassive Black Hole Binaries with GRAVITY}},
  author = {GRAVITY Collaboration and K. Abd El Dayem and N. Aimar and A. Berdeu and J. -P. Berger and G. Bourdarot and W. Brandner and Y. Cao and C. Correia and Q. D'Amato and R. Davies and D. Defrère and A. Drescher and F. Eisenhauer and M. Fabricius and H. Feuchtgruber and S. Flesch and N. M. Förster Schreiber and A. Foschi and Q. Fournier and P. Garcia and R. Garcia Lopez and R. Genzel and S. Gillessen and F. Gonté and X. Haubois and S. F. Hönig and L. C. Ho and M. Houllé and S. Joharle and J. Kammerer and A. Kaufer and P. Kervella and J. Kolb and L. Kreidberg and L. Labadie and S. Lacour and O. Lai and R. Laugier and J. B. Le Bouquin and J. Leftley and R. Li and K. Li and B. Lopez and D. Lutz and F. Mannucci and F. Mang and A. Mérand and F. Millour and M. Montargès and N. Morujão and H. Nowacki and M. Nowak and S. Oberti and J. Osorno and T. Ott and C. Paladini and S. Pappert and T. Paumard and K. Perraut},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.14174},
  eprint = {2610.14174},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.14174},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Searching for Nearby Supermassive Black Hole Binaries with GRAVITY
AU  - GRAVITY Collaboration
AU  - K. Abd El Dayem
AU  - N. Aimar
AU  - A. Berdeu
AU  - J. -P. Berger
AU  - G. Bourdarot
AU  - W. Brandner
AU  - Y. Cao
AU  - C. Correia
AU  - Q. D'Amato
AU  - R. Davies
AU  - D. Defrère
AU  - A. Drescher
AU  - F. Eisenhauer
AU  - M. Fabricius
AU  - H. Feuchtgruber
AU  - S. Flesch
AU  - N. M. Förster Schreiber
AU  - A. Foschi
AU  - Q. Fournier
AU  - P. Garcia
AU  - R. Garcia Lopez
AU  - R. Genzel
AU  - S. Gillessen
AU  - F. Gonté
AU  - X. Haubois
AU  - S. F. Hönig
AU  - L. C. Ho
AU  - M. Houllé
AU  - S. Joharle
AU  - J. Kammerer
AU  - A. Kaufer
AU  - P. Kervella
AU  - J. Kolb
AU  - L. Kreidberg
AU  - L. Labadie
AU  - S. Lacour
AU  - O. Lai
AU  - R. Laugier
AU  - J. B. Le Bouquin
AU  - J. Leftley
AU  - R. Li
AU  - K. Li
AU  - B. Lopez
AU  - D. Lutz
AU  - F. Mannucci
AU  - F. Mang
AU  - A. Mérand
AU  - F. Millour
AU  - M. Montargès
AU  - N. Morujão
AU  - H. Nowacki
AU  - M. Nowak
AU  - S. Oberti
AU  - J. Osorno
AU  - T. Ott
AU  - C. Paladini
AU  - S. Pappert
AU  - T. Paumard
AU  - K. Perraut
PY  - 2026
DA  - 2026/10/09
PB  - arXiv
DO  - 10.48550/arxiv.2610.14174
UR  - https://arxiv.org/abs/2610.14174
AB  - 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_bin<16.5% for GRAVITY-detectable binaries among bright nearby AGN (K<12.5) at separations of ∼1-$100$~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_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.
ER  -