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Title: The black hole mass and the stellar ring in NGC 3706

We determine the mass of the nuclear black hole (M) in NGC 3706, an early-type galaxy with a central surface brightness minimum arising from an apparent stellar ring, which is misaligned with respect to the galaxy's major axis at larger radii. We fit new HST/STIS and archival data with axisymmetric orbit models to determine M, mass-to-light ratio (Y {sub V}), and dark matter halo profile. The best-fit model parameters with 1σ uncertainties are M=(6.0{sub −0.9}{sup +0.7})×10{sup 8} M{sub ⊙} and Υ{sub V}=6.0±0.2 M{sub ⊙} L{sub ⊙,V}{sup −1} at an assumed distance of 46 Mpc. The models are inconsistent with no black hole at a significance of Δχ{sup 2} = 15.4 and require a dark matter halo to adequately fit the kinematic data, but the fits are consistent with a large range of plausible dark matter halo parameters. The ring is inconsistent with a population of co-rotating stars on circular orbits, which would produce a narrow line-of-sight velocity distribution (LOSVD). Instead, the ring's LOSVD has a small value of |V|/σ, the ratio of mean velocity to velocity dispersion. Based on the observed low |V|/σ, our orbit modeling, and a kinematic decomposition of the ring from the bulge, we conclude that themore » stellar ring contains stars that orbit in both directions. We consider potential origins for this unique feature, including multiple tidal disruptions of stellar clusters, a change in the gravitational potential from triaxial to axisymmetric, resonant capture and inclining of orbits by a binary black hole, and multiple mergers leading to gas being funneled to the center of the galaxy.« less
Authors:
;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  2. Department of Astronomy, University of Texas, 1 University Station C1400, Austin, TX 78712 (United States)
  3. National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States)
  4. Universitäts-Sternwarte München, Ludwig-Maximilians-Universität, Scheinerstr. 1, D-81679 München (Germany)
  5. Institute for Advanced Study, Einstein Dr., Princeton, NJ 08540 (United States)
Publication Date:
OSTI Identifier:
22348096
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 781; 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; CAPTURE; DECOMPOSITION; DISPERSIONS; DISTANCE; DISTRIBUTION; GALAXIES; GALAXY NUCLEI; MASS; NONLUMINOUS MATTER; ORBITS; ORIGIN; SIMULATION; STARS; VELOCITY; VISIBLE RADIATION