FOKKER–PLANCK MODELS FOR M15 WITHOUT A CENTRAL BLACK HOLE: THE ROLE OF THE MASS FUNCTION
FOKKER–PLANCK MODELS FOR M15 WITHOUT A CENTRAL BLACK HOLE: THE ROLE OF THE MASS FUNCTION
复制标题
无中心黑洞的 M15 福克-普朗克模型：质量函数的作用
DOI：
10.1088/0004-637x/732/2/67
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
P. Lugger
中科院分区：
文献类型：
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作者：
B. Murphy;H. Cohn;P. Lugger
我们发展了一套动态演化的Fokker-Planck模型，用于研究球状星星团M15的中心黑洞是否符合哈勃空间望远镜（HST）对恒星空间分布和运动学的观测。正如我们以前的工作报告Dull等人，我们发现中心黑洞是不需要的。利用HST研究的局部质量函数数据，我们还推导了全局初始恒星质量函数。由于极端的质量分离，局部质量函数在每个位置都不同于整体质量函数。除了再现观测到的质量函数，该模型还提供了良好的适合的恒星计数和速度色散的配置文件，毫秒脉冲星加速度。我们解决的问题，大中子星星人口在我们以前的福克-普朗克模型M15。我们发现，良好的模型拟合可以得到少至1600中子星，这对应于我们的最佳拟合初始质量函数的初始人口的5%的保留分数。这些模型包含了大量的大质量白色矮星，质量范围高达120万。大质量白色矮星和中子星的共同贡献提供了重现HST测量中心速度色散剖面所需的引力势。
We have developed a set of dynamically evolving Fokker–Planck models for the collapsed-core globular star cluster M15, which directly address the issue of whether a central black hole is required to fit Hubble Space Telescope (HST) observations of the stellar spatial distribution and kinematics. As in our previous work reported by Dull et al., we find that a central black hole is not needed. Using local mass-function data from HST studies, we have also inferred the global initial stellar mass function. As a consequence of extreme mass segregation, the local mass functions differ from the global mass function at every location. In addition to reproducing the observed mass functions, the models also provide good fits to the star-count and velocity-dispersion profiles, and to the millisecond pulsar accelerations. We address concerns about the large neutron star populations adopted in our previous Fokker–Planck models for M15. We find that good model fits can be obtained with as few as 1600 neutron stars; this corresponds to a retention fraction of 5% of the initial population for our best-fit initial mass function. The models contain a substantial population of massive white dwarfs, that range in mass up to 1.2M☉. The combined contribution by the massive white dwarfs and neutron stars provides the gravitational potential needed to reproduce HST measurements of the central velocity-dispersion profile.