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Title: SUPERMASSIVE BLACK HOLE BINARY EVOLUTION IN AXISYMMETRIC GALAXIES: THE FINAL PARSEC PROBLEM IS NOT A PROBLEM

During a galaxy merger, the supermassive black hole (SMBH) in each galaxy is thought to sink to the center of the potential and form an SMBH binary; this binary can eject stars via three-body scattering, bringing the SMBHs ever closer. In a static spherical galaxy model, the binary stalls at a separation of about a parsec after ejecting all the stars in its loss cone-this is the well-known final parsec problem. Earlier work has shown that the centrophilic orbits in triaxial galaxy models are key in refilling the loss cone at a high enough rate to prevent the black holes from stalling. However, the evolution of binary SMBHs has never been explored in axisymmetric galaxies, so it is not clear if the final parsec problem persists in these systems. Here we use a suite of direct N-body simulations to follow SMBH binary evolution in galaxy models with a range of ellipticity. For the first time, we show that mere axisymmetry can solve the final parsec problem; we find the SMBH evolution is independent of N for an axis ratio of c/a = 0.8, and that the SMBH binary separation reaches the gravitational radiation regime for c/a = 0.75.
Authors:
 [1] ;  [2] ; ;  [3]
  1. Department of Space Science, Institute of Space Technology, P.O. Box 2750 Islamabad (Pakistan)
  2. Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States)
  3. Astronomisches Rechen-Institut, Zentrum fuer Astronomie, University of Heidelberg, Moenchhof-Strasse 12-14, D-69120 Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22131014
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AXIAL SYMMETRY; BLACK HOLES; GALAXIES; GRAVITATIONAL RADIATION; LOSS CONE; ORBITS; SCATTERING; SPHERICAL CONFIGURATION; STAR EVOLUTION; STARS; THREE-BODY PROBLEM