论文标题
在z> 4的银河系大小的星系中，恒星簇形成 - I。
Stellar cluster formation in a Milky Way-sized galaxy at z>4 -- I. The proto-globular cluster population and the imposter amongst us
论文作者
论文摘要
Redshift $ Z> 4 $的球形簇（GCS）的形成历史仍然是一个未解决的问题。在这项工作中，我们使用宇宙学$ n $ - 体流体动力学``Zoom-In''模拟Gigaeris研究围绕银河系大小的银河系祖先的祖先候选者的特性和形成。该模拟采用了平滑粒子流体动力学的现代实现，包括金属线冷却，金属和热扩散，并允许在星形簇的尺度上解析系统。我们将原始GC候选系统定义为具有重力限制的恒星系统，带有Baryonic质量分数$ f _ {\ rm B} \ geq 0.75 $和Stellar Velocity分散$σ_{\ Star} <20 $ km S $ s $ s $ s $^{ - 1} $。在$ z = 4.4 $时，我们识别满足我们条件的9个系统，所有这些系统从主要主机的中心从10 kpc到30 kpc之间形成。他们的重质质量在$ 10^5 $ - $ 10^7 $ m $ _ {\ odot} $的范围内。在模拟结束时，它们仍然具有相对较低的恒星质量（$ m _ {\ star} \ sim 10^4 $ - $ 10^5 $ M $ _ {\ odot} $）和金属（$ -1.8 \ -1.8 \ sillssim {\ sillssim {\ rm [fe/h]}}除一个已确定的系统外，所有已确定的系统似乎与在圆形区域的主星系上积聚的气体丝相关，并以$ z = 5-4 $形成。例外是最古老的对象，它似乎是一个被剥离的紧凑型矮星银河系，它与$ z = 5.8 $和$ z = 5.2 $之间的主要光环相互作用，并且由于潮汐质量损失而失去了整个暗物质内容。
The formation history of globular clusters (GCs) at redshift $z > 4$ remains an unsolved problem. In this work, we use the cosmological, $N$-body hydrodynamical ``zoom-in'' simulation GigaEris to study the properties and formation of proto-GC candidates in the region surrounding the progenitor of a Milky Way-sized galaxy. The simulation employs a modern implementation of smoothed-particle hydrodynamics, including metal-line cooling and metal and thermal diffusion and allows to resolve systems at the scale of star clusters. We define proto-GC candidate systems as gravitationally bound stellar systems with baryonic mass fraction $F_{\rm b} \geq 0.75$ and stellar velocity dispersion $σ_{\star} < 20$ km s$^{-1}$. At $z=4.4$ we identify 9 systems which satisfy our criteria, all of which form between 10 kpc to 30 kpc from the centre of the main host. Their baryonic masses are in the range $10^5$- $10^7$ M$_{\odot}$. By the end of the simulation, they still have a relatively low stellar mass ($M_{\star} \sim 10^4$--$10^5$ M$_{\odot}$) and a metallicity ($-1.8 \lesssim {\rm [Fe/H]} \lesssim -0.8$) similar to the blue Galactic GCs. All of the identified systems except one appear to be associated with gas filaments accreting onto the main galaxy in the circum-galactic region, and formed at $z=5-4$. The exception is the oldest object, which appears to be a stripped compact dwarf galaxy that has interacted with the main halo between $z = 5.8$ and $z=5.2$ and has lost its entire dark matter content due to tidal mass loss.
