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arXiv 1909.04192astro-ph.GAgr-qc
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球状星团的渐进运动学：塔利-费舍尔关系的出现

Asymptotic kinematics of Globular Clusters: the emergence of a Tully-Fisher relation

X. Hernandez, A. J. Lara-D.

备注：
9 pages, 8 figures, 1 table. Revised version accepted for publication in MNRAS
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摘要：

利用最近获得的40个高质量的银河系球状星团速度色散剖面的均匀样本，我们研究了这些系统外围的低重力加速度区。我们发现，一个简单的经验配置文件具有中心高斯分量和一个恒定的大半径渐近线，$σ_{\infty}$，准确地描述了所观察到的速度色散配置文件的品种。我们使用已发表的人口合成模型，仔细定制每个单独的集群，估计质量与总恒星质量，$M$，推断光比。我们得到了一个清晰的标度，让人想起银河Tully-Fisher关系的$σ_{\infty}( km s^{-1})= 0.084^{+0.075}_{-0.040} (M/M_{\odot})^{0.3 \pm 0.051} $，这是有趣的比较深MOND极限的$σ_{\infty} (km s^{-1})=0.2(M/M_{\odot})^{0.25}$。在牛顿的解释下，我们的结果构成了对模型的进一步限制，在这些模型中，初始条件是为了产生今天观察到的外部扁平化。在一个修改的重力计划，作为球状星团研究的不是孤立的对象在深MOND制度，所获得的结果指向修改的重力MOND的外场效应不出现，或被大大抑制。

英文摘要：

Using a recent homogeneous sample of 40 high quality velocity dispersion profiles for Galactic globular clusters, we study the low gravitational acceleration regime relevant to the outskirts of these systems. We find that a simple empirical profile having a central Gaussian component and a constant large radius asymptote, $σ_{\infty}$, accurately describes the variety of observed velocity dispersion profiles. We use published population synthesis models, carefully tailored to each individual cluster, to estimate mass to light ratios from which total stellar masses, $M$, are inferred. We obtain a clear scaling, reminiscent of the galactic Tully-Fisher relation of $σ_{\infty}( km s^{-1})= 0.084^{+0.075}_{-0.040} (M/M_{\odot})^{0.3 \pm 0.051} $, which is interesting to compare to the deep MOND limit of $σ_{\infty} (km s^{-1})=0.2(M/M_{\odot})^{0.25}$. Under a Newtonian interpretation, our results constitute a further restriction on models where initial conditions are crafted to yield the outer flattening observed today. Within a modified gravity scheme, as the globular clusters studied are not isolated objects in the deep MOND regime, the results obtained point towards a modified gravity where the external field effect of MOND does not appear, or is much suppressed.

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