The state of globular clusters at birth – II. Primordial binaries
The state of globular clusters at birth – II. Primordial binaries
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DOI：
10.1093/mnras/stu2110
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发表时间：
2014-10
影响因子：
4.8
通讯作者：
N. Leigh;M. Giersz;M. Marks;J. Webb;A. Hypki;C. Heinke;P. Kroupa;A. Sills
中科院分区：
文献类型：
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作者：
N. Leigh;M. Giersz;M. Marks;J. Webb;A. Hypki;C. Heinke;P. Kroupa;A. Sills
在本文中，我们约束了银河系球状星团中原始双星族的性质。使用MOCCA蒙特卡洛代码进行星团演化，我们的模拟覆盖了当前星团总质量的三十年。我们的结果与Milone等人（2012）的观测结果进行了比较，他们使用光度双星总体作为真实潜在分布的代理，以检验数据与接近单位的通用初始双星分数和Kroupa（1995）的双星轨道参数分布相一致的假设。除了少数可能的异常值外，我们发现数据与普遍性假设是一阶一致的。具体地说，在半质量半径内的现在的二元分数可以被复制，假设高的初始二元分数接近1，主要是软二元成分，如克鲁巴分布，结合高的初始密度（104 -10 6 M⊙pc−3），或者低的初始二元分数（- 5-10%），主要是硬二元成分，结合中等的初始密度，接近它们现在的值（10 2 -10 3 M⊙pc−3）。这种明显的简并可以用半质量半径外的二元分数来打破，只有具有显著软分量的高初始二元分数与高初始密度相结合，才能有助于再现所观察到的半质量半径外二元分数与星团总质量之间的反相关。我们使用模拟的现今双星轨道参数分布和Leigh等人（2012）首次引入的技术进一步说明，硬双星和软双星的相对分数可用于进一步约束初始星团密度和初始质量密度关系。我们的结果倾向于初始质量-密度关系
In this paper, we constrain the properties of primordial binary populations in Galactic globular clusters. Using the MOCCA Monte Carlo code for cluster evolution, our simulations cover three decades in present-day total cluster mass. Our results are compared to the observations of Milone et al. (2012) using the photometric binary populations as proxies for the true underlying distributions, in order to test the hypothesis that the data are consistent with an universal initial binary fraction near unity and the binary orbital parameter distributions of Kroupa (1995). With the exception of a few possible outliers, we find that the data are to first-order consistent with the universality hypothesis. Specifically, the present-day binary fractions inside the half-mass radius can be reproduced assuming either high initial binary fractions near unity with a dominant soft binary component as in the Kroupa distribution combined with high initial densities (10 4 -10 6 M⊙ pc −3 ), or low initial binary fractions (� 5-10%) with a dominant hard binary component combined with moderate initial densities near their present-day values (10 2 -10 3 M⊙ pc −3 ). This apparent degeneracy can potentially be broken using the binary fractions outside the half-mass radius only high initial binary fractions with a significant soft component combined with high initial densities can contribute to reproducing the observed anti-correlation between the binary fractions outside the half-mass radius and the total cluster mass. We further illustrate using the simulated present-day binary orbital parameter distributions and the technique first introduced in Leigh et al. (2012) that the relative fractions of hard and soft binaries can be used to further constrain both the initial cluster density and the initial mass-density relation. Our results favour an initial mass-density relation of