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 $M_{\rm vir}(z=0)=10^{13.5} M_\odot$. We show that, in contrast with the accreted stellar halo, the accretion events contributing to the assembly of the halo populations of red and blue GCs are increasingly biased towards low satellite-to-host virial mass ratios. As a direct consequence, and in agreement with observations, our cosmologically accreted blue GC populations are systematically more extended and have higher velocity dispersion than for red GCs, due to the reduced efficiency of dynamical friction on minor mergers. For the same reason, the half-number radii of both GC populations are found to correlate with halo assembly history. GC line-of-sight velocity distributions featuring negative values of the kurtosis \kappa, as recently observed, are ubiquitous in our simple 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 ($\beta(r<10~{\rm kpc})\sim0.2$) to strongly radially anisotropic at large galactocentric distances ($\beta(r>30~{\rm kpc})\gtrsim0.6$). Show Chinese abstract

Abstract: 我们使用蒙特卡罗\Lambda CDM 演化历史、次要合并的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，其中$M_{\rm vir}(z=0)=10^{13.5} M_\odot$。 我们表明，与吸积的恒星晕相反，对红和蓝球状星团晕种群的形成有贡献的吸积事件越来越倾向于低卫星-主机的维里质量比。 作为直接结果，并且与观测结果一致，由于在次要合并中动力摩擦效率降低，我们的宇宙吸积蓝球状星团种群系统地更广泛，速度弥散更高。 出于同样的原因，两个球状星团种群的半数半径被发现与晕的演化历史相关。 具有负的峰度值\kappa 的球状星团视线速度分布，如最近所观察到的，在我们的简单模型中是普遍存在的。 因此，\kappa <0 并不与吸积情景相矛盾，事实上是次要合并重要贡献的特征。 然而，我们的吸积球状星团种群仍然主要呈径向偏差，各向异性参数\beta 的分布中心（$\beta(r<10~{\rm kpc})\sim0.2$）为轻微径向各向异性，在大的银河中心距离处（$\beta(r>30~{\rm kpc})\gtrsim0.6$）则表现出强烈的径向各向异性。