Title: Globular cluster populations and the kinematical fingerprints of minor mergers Show Chinese title

Title: 球状星团群体和次要合并的运动学特征

Abstract: We use Monte Carlo $\Lambda$CDM assembly histories, minor-merger N-body simulations and empirical relations between halo mass and the globular cluster (GC) abundance to study the kinematical properties of halo GCs in massive galaxies, with $M_{vir}(z=0)=10^{13.5}M_\odot$. While the accreted stellar halo is dominated by the contributions of massive satellites, we show that satellites with low virial mass (i.e. low satellite-to-host virial mass ratio, VMRs) are important contributors to the population of accreted GCs. The relative contribution of accretion events with low VMRs is highest for the halo population of blue GCs and gradually decreases for red GCs and accreted stars. As a consequence of the reduced efficiency of dynamical friction on minor mergers, our populations of cosmologically accreted blue GCs are systematically more spatially extended and have higher velocity dispersions than for red GCs, in agreement with observations. For the same reason, assembly histories including a higher fraction of minor mergers result in more spatially extended GC populations. GC line-of-sight velocity distributions featuring negative values of the kurtosis $\kappa$, as recently observed, are ubiquitous in our models. Therefore, $\kappa<0$ is not at odds with an accretion scenario, and in fact a fingerprint of the important contribution of minor mergers. However, our populations of accreted GCs remain mostly radially biased, with profiles of the anisotropy parameter $\beta$ that are mildly radial in the center ($\beta(r<10~{\rm kpc})\sim0.2$) and strongly radially anisotropic at large galactocentric distances ($\beta(r>30~{\rm kpc})\gtrsim0.6$), for both red and blue populations. Show Chinese abstract

Abstract: 我们使用蒙特卡洛$\Lambda$CDM合并历史、小并合N体模拟以及晕质量与球状星团（GC）丰度之间的经验关系来研究大质量星系中晕球状星团的动力学特性，具有$M_{vir}(z=0)=10^{13.5}M_\odot$。 虽然吸积的恒星晕主要由大卫星的贡献主导，但我们表明低维里质量的卫星（即低卫星-主机维里质量比，VMRs）是吸积球状星团种群的重要贡献者。 低VMR的吸积事件对蓝球状星团晕种群的相对贡献最高，并且对于红球状星团和吸积恒星逐渐减少。 由于在小并合中动力摩擦效率较低，我们的宇宙学吸积蓝球状星团种群在空间上系统地更扩展，并且具有比红球状星团更高的速度弥散度，这与观测结果一致。 出于同样的原因，包含更高比例小并合的合并历史会导致更扩展的球状星团种群。 最近观测到的具有负峰度值$\kappa$的球状星团视线速度分布，在我们的模型中是普遍存在的。 因此，$\kappa<0$并不与吸积情景矛盾，实际上是小并合重要贡献的一个特征。 然而，我们的吸积球状星团种群仍然主要呈径向偏倚，各向异性参数$\beta$的分布在中心（$\beta(r<10~{\rm kpc})\sim0.2$）呈轻微径向各向异性，在大星系中心距离处（$\beta(r>30~{\rm kpc})\gtrsim0.6$）则呈强烈径向各向异性，适用于红球状星团和蓝球状星团。