Determining subparsec supermassive black hole binary orbits with infrared interferometry

MPG.PuRe (Max Planck Society)

Abstract

Radial-velocity monitoring has revealed the presence of moving broad emission lines in some quasars, potentially indicating the presence of a subparsec binary system. Phase-referenced, near-infrared interferometric observations could map out the binary orbit by measuring the photocenter difference between a broad emission line and the hot dust continuum. We show that astrometric data over several years may be able to detect proper motions and accelerations, confirming the presence of a binary and constraining system parameters. The brightness, redshifts, and astrometric sizes of current candidates are well matched to the capabilities of the upgraded Very Large Telescope Interferometer/GRAVITY+ instrument, and we identify a first sample of 10 possible candidates. The astrometric signature depends on the morphology and evolution of hot dust emission in supermassive black hole binary systems. Measurements of the photocenter offset may reveal binary motion whether the hot dust emission region is fixed to the inner edge of the circumbinary disk, or moves in response to the changing irradiation pattern from an accreting secondary black hole.

Authors 7

1. Jason Dexter corresponding

   Joint Institute for Laboratory Astrophysics · University of Colorado Boulder

   Affiliation as printed

   JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309, USA

2. Dieter Lutz

   Max Planck Society · Max Planck Institute for Extraterrestrial Physics

   Affiliation as printed

   Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society

   Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany

3. Thomas Shimizu

   Max Planck Society · Max Planck Institute for Extraterrestrial Physics

   Affiliation as printed

   Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society

   Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany

4. R. Davies

   Max Planck Society · Max Planck Institute for Extraterrestrial Physics

   Affiliation as printed

   Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society

   Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany

5. P. T. de Zeeuw corresponding Aachen Sterrewacht Leiden

   Leiden University · Max Planck Society · Max Planck Institute for Extraterrestrial Physics · Leiden Observatory

   Affiliation as printed

   Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society

   Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany

   Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands

6. R. Genzel

   Max Planck Society · Max Planck Institute for Extraterrestrial Physics · University of California, Berkeley

   Affiliation as printed

   Infrared and Submillimeter Astronomy, MPI for Extraterrestrial Physics, Max Planck Society

   Departments of Physics and Astronomy, Le Conte Hall, University of California, Berkeley, CA 94720, USA

   Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching, Germany

7. O. Pfuhl

   European Southern Observatory

   Affiliation as printed

   European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany