从矮椭球到cDs：在LCDM宇宙学中模拟星系人口
From dwarf spheroidals to cDs: Simulating the galaxy population in a LCDM cosmology
摘要：
我们应用更新的半解析星系形成模型，同时存储的晕/subhalo合并千年和千禧-II模拟树。它们的质量分辨率相差125倍，从而可以明确测试分辨率对预测星系属性的影响。我们已经修改了治疗之间的过渡的快速下降和冷却流制度的气体吸积，膨胀和气体和恒星盘的大小，超新星的反馈，中央和卫星状态之间的过渡星系落入更大的系统，气体和恒星剥离一旦他们成为卫星。合理的效率值和标度参数不仅与观测到的恒星质量超过5个数量级、光度超过9个数量级的低红移星系丰度非常吻合，而且与观测到的银河系卫星丰度也非常吻合。这表明，再电离效应可能不需要解决“失踪卫星”的问题，也许，除了最微弱的物体。同样的模型也与观测到的大规模星系团成团现象相吻合，这是恒星质量和颜色的函数。对于大质量星系来说，在30 kpc以下仍然非常适合。然而，对于M* < 6 x 10^10 Msun，模型高估了低于1 Mpc尺度的聚类，这表明模拟中采用的sigma_8（0.9）过高。星系分布在丰富的集群同意之间的模拟和匹配的观察，但只有当星系没有暗物质subhalos（所谓的孤儿）包括在内。我们的模型预测了低质量星系中的被动部分比观测到的要大，以及在z~0.6之外的~ 10^10 Msun星系过多，反映了恒星形成率建模方式的不足。
英文摘要：
We apply updated semi-analytic galaxy formation models simultaneously to the stored halo/subhalo merger trees of the Millennium and Millennium-II simulations. These differ by a factor of 125 in mass resolution, allowing explicit testing of resolution effects on predicted galaxy properties. We have revised the treatments of the transition between the rapid infall and cooling flow regimes of gas accretion, of the sizes of bulges and of gaseous and stellar disks, of supernova feedback, of the transition between central and satellite status as galaxies fall into larger systems, and of gas and star stripping once they become satellites. Plausible values of efficiency and scaling parameters yield an excellent fit not only to the observed abundance of low-redshift galaxies over 5 orders of magnitude in stellar mass and 9 magnitudes in luminosity, but also to the observed abundance of Milky Way satellites. This suggests that reionisation effects may not be needed to solve the "missing satellite" problem except, perhaps, for the faintest objects. The same model matches the observed large-scale clustering of galaxies as a function of stellar mass and colour. The fit remains excellent down to ~30kpc for massive galaxies. For M* < 6 x 10^10Msun, however, the model overpredicts clustering at scales below 1 Mpc, suggesting that the sigma_8 adopted in the simulations (0.9) is too high. Galaxy distributions within rich clusters agree between the simulations and match those observed, but only if galaxies without dark matter subhalos (so-called orphans) are included. Our model predicts a larger passive fraction among low-mass galaxies than is observed, as well as an overabundance of ~10^10Msun galaxies beyond z~0.6, reflecting deficiencies in the way star-formation rates are modelled.
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