论文标题
星系模拟中星形簇的潮汐破坏
Tidal disruption of star clusters in galaxy formation simulations
论文作者
论文摘要
我们使用银河系大小的星系的宇宙学模拟来研究大量恒星簇所经历的潮汐场的演变。在编队后，我们模拟中的簇在头几百个Myr中经历了最强的潮汐力，当时潮汐张量的最大特征值达到了几次$ 10^4 $ gyr $^{ - 2} $。大约1 Gyr之后，潮汐场高原的值较低，中间$λ_{\ rm m} \ sim 3 \ times 10^3 $ gyr $^{ - 2} $。时间簇的时间群以高潮汐强度花费（$λ_ {\ rm m}> 3 \ times 10^4 $ gyr $^{ - 2} $也随着年龄的增长而下降，从$ \ sim $ \ sim $ \ sim $ 20％立即形成后，在1 gyr后立即增加到1％以下。在早期，原位和现场群集都经历了类似的潮汐场，而在老年时，由于其在宿主星系中的较低轨道，因此一般的原位群集在一般情况下经历了更强的潮汐场。这种差异反映在集群的存活中：我们研究了在模拟运行时计算出的群集破坏，发现相同初始质量的ex恒星簇通常最终在最后一个可用的模拟快照中以更高的绑定分数而不是原位。
We investigate the evolution of the tidal field experienced by massive star clusters using cosmological simulations of Milky Way-sized galaxies. Clusters in our simulations experience the strongest tidal force in the first few hundred Myr after formation, when the maximum eigenvalue of the tidal tensor reaches several times $10^4$ Gyr$^{-2}$. After about 1 Gyr the tidal field plateaus at a lower value, with the median $λ_{\rm m} \sim 3 \times 10^3$ Gyr$^{-2}$. The fraction of time clusters spend in high tidal strength ($λ_{\rm m} > 3 \times 10^4$ Gyr$^{-2}$) regions also decreases with their age from $\sim$20% immediately after formation to less than 1% after 1 Gyr. At early ages both the in situ and ex situ clusters experience similar tidal fields, while at older ages the in situ clusters in general experience stronger tidal field due to their lower orbits in host galaxy. This difference is reflected in the survival of clusters: we looked into cluster disruption calculated in simulation runtime and found that ex situ star clusters of the same initial mass typically end up with higher bound fraction at the last available simulation snapshot than the in situ ones.
