期刊
ASTROPHYSICAL JOURNAL
卷 718, 期 2, 页码 739-761出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/718/2/739
关键词
Galaxy: center; Galaxy: evolution; Galaxy: kinematics and dynamics; Galaxy: structure
资金
- NSF [AST-0807910]
- NASA [NNX07AH15G]
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-circle dot 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*.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据