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arXiv 2005.09410astro-ph.GA
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M87球状星团的离散化学动力学模型：扩展到~ 400 kpc的动力学

A discrete chemo-dynamical model of M87's globular clusters: Kinematics extending to ~ 400 kpc

Chao Li, Ling Zhu, R. J. Long, Shude Mao, Eric W. Peng, Marc Sarzi, Glenn van de Ven, Hongxin Zhang, Rui Guo, Xiangxiang Xue, Alessia Longobardi, Patrick Côté, … 展开作者

Chao Li, Ling Zhu, R. J. Long, Shude Mao, Eric W. Peng, Marc Sarzi, Glenn van de Ven, Hongxin Zhang, Rui Guo, Xiangxiang Xue, Alessia Longobardi, Patrick Côté, Laura Ferrarese, Chengze Liu, Stephen Gwyn, Sungsoon Lim, Youkyung Ko

发表信息：
MNRAS, 2020, 492(2):2775-2795
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摘要：

我们研究了巨大的椭圆星系M87（NGC 4486）的质量分布和运动学的离散化学动力学，轴对称金斯方程模拟。我们的星表包括894个球状星团（GC），其投影半径为$\sim 430$ kpc，具有视线速度和颜色，以及主星系中央$2.4$ kpc内的多单元光谱探测器（MUSE）积分场单元数据。我们的模型的引力势是一个发光物质的潜力与不同的质量与光的主星系，一个超大质量黑洞和暗物质（DM）的潜力与尖或核心DM晕的组合。具有尖瓣或核心DM晕圈的最佳拟合模型未显示显著差异，两者均可接受。我们得到了$(2.16 \pm 0.38) \times 10^{13} M_{\odot}$的总质量在$\sim$ 400 kpc范围内。通过加入恒星质光比梯度，DM分数在$1\,R_e^{\rm maj}$（半光等照度线长轴，14.2 kpc）内从$\sim$ 26%（无梯度）增加到$\sim$ 73%，在$5\,R_e^{\rm maj}$（71.2 kpc）内从$\sim$ 84%增加到$\sim$ 94%。红色GC在$V_{\rm max}/σ\sim$ 0.4时具有中等旋转，蓝色GC在$V_{\rm max}/σ\sim$ 0.1时具有弱旋转。红色GC具有切向速度弥散各向异性，而蓝色GC与几乎各向同性一致。我们的研究结果表明，红色GC更有可能在原位生成，而蓝色GC更有可能被吸积。

英文摘要：

We study the mass distribution and kinematics of the giant elliptical galaxy M87 (NGC 4486) using discrete chemo-dynamical, axisymmetric Jeans equation modelling. Our catalogue comprises 894 globular clusters (GCs) extending to a projected radius of $\sim 430$ kpc with line-of-sight velocities and colours, and Multi Unit Spectroscopic Explorer (MUSE) integral field unit data within the central $2.4$ kpc of the main galaxy. The gravitational potential for our models is a combination of a luminous matter potential with a varying mass-to-light ratio for the main galaxy, a supermassive black hole and a dark matter (DM) potential with a cusped or cored DM halo. The best-fitting models with either a cusped or a cored DM halo show no significant differences and both are acceptable. We obtain a total mass of $(2.16 \pm 0.38) \times 10^{13} M_{\odot}$ within $\sim$ 400 kpc. By including the stellar mass-to-light ratio gradient, the DM fraction increases from $\sim$ 26 percent (with no gradient) to $\sim$ 73 percent within $1\,R_e^{\rm maj}$ (major axis of half-light isophote, 14.2 kpc), and from $\sim$ 84 percent to $\sim$ 94 percent within $5\,R_e^{\rm maj}$ (71.2 kpc). Red GCs have moderate rotation with $V_{\rm max}/σ\sim$ 0.4, and blue GCs have weak rotation with $V_{\rm max}/σ\sim$ 0.1. Red GCs have tangential velocity dispersion anisotropy, while blue GCs are consistent with being nearly isotropic. Our results suggest that red GCs are more likely to be born in-situ, while blue GCs are more likely to be accreted.

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