THE DISTRIBUTION OF STARS AND STELLAR REMNANTS AT THE GALACTIC CENTER

Journal Article · Sun Aug 01 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/718/2/739· OSTI ID:21455112

Merritt, David ^[1]

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1. Department of Physics and Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States)

Motivated by recent observations that suggest a low density of old stars around the Milky Way supermassive black hole (SMBH), models for the nuclear star cluster are considered that have not yet reached a steady state under the influence of gravitational encounters. A core of initial radius 1-1.5 pc evolves to a size of approximately 0.5 pc after 10 Gyr, roughly the size of the observed core. The absence of a Bahcall-Wolf cusp is naturally explained in these models, without the need for fine-tuning or implausible initial conditions. In the absence of a cusp, the time for a 10 M{sub sun} black hole (BH) to spiral in to the Galactic center from an initial distance of 5 pc can be much greater than 10 Gyr. Assuming that the stellar BHs had the same phase-space distribution initially as the stars, their density after 5-10 Gyr is predicted to rise very steeply going into the stellar core, but could remain substantially below the densities inferred from steady-state models that include a steep density cusp in the stars. Possible mechanisms for the creation of the parsec-scale initial core include destruction of stars on centrophilic orbits in a pre-existing triaxial nucleus, inhibited star formation near the SMBH, or ejection of stars by a massive binary. The implications of these models are discussed for the rates of gravitational-wave inspiral events, as well as other physical processes that depend on a high density of stars or stellar-mass BHs near SgrA*.

• OSTI ID: 21455112
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 718; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
EVOLUTION
GALACTIC EVOLUTION
GALAXIES
GRAVITATIONAL WAVES
MATHEMATICAL SPACE
MILKY WAY
PHASE SPACE
SPACE
STAR CLUSTERS
STARS
STEADY-STATE CONDITIONS