缩小的许多表现：层次星系形成模型与观测相对抗
The Many Manifestations of Downsizing: Hierarchical Galaxy Formation Models confront Observations
摘要：
[摘要]人们普遍认为，几条观测证据指向宇宙时间内星系形成过程的“缩小”（DS）。这种行为有时被称为“反层次”，并与冷暗物质模型中的暗物质结构的“自下而上”组装形成对比。在本文中，我们讨论了三种不同的观测证据，已被描述为DS：恒星质量组装，恒星形成率和年龄的恒星星族在本地星系。我们比较了广泛的汇编可用的数据集与三个不同的半解析模型的预测星系形成内的Lambda CDM框架。在这些数据中，我们只能看到恒星质量和恒星形成率方面的微弱证据。我们发现，当恒星质量和SFR的观测误差被考虑在内，模型可以接受地再现大质量星系的演化，在整个红移范围内，我们认为。然而，低质量星系在模型中形成得太早，并且在后期过于被动。因此，该模型不正确地再现DS的恒星质量或考古DS的趋势，而他们定性地再现质量依赖的演化的SFR。我们证明，这些差异不仅是由于卫星星系的治疗不佳，但主要是连接到过度有效的形成中心星系的高红移晕的圆速度~100-200公里/秒。[删节]
英文摘要：
[abridged] It has been widely claimed that several lines of observational evidence point towards a "downsizing" (DS) of the process of galaxy formation over cosmic time. This behavior is sometimes termed "anti-hierarchical", and contrasted with the "bottom-up" assembly of the dark matter structures in Cold Dark Matter models. In this paper we address three different kinds of observational evidence that have been described as DS: the stellar mass assembly, star formation rate and the ages of the stellar populations in local galaxies. We compare a broad compilation of available data-sets with the predictions of three different semi-analytic models of galaxy formation within the Lambda-CDM framework. In the data, we see only weak evidence at best of DS in stellar mass and in star formation rate. We find that, when observational errors on stellar mass and SFR are taken into account, the models acceptably reproduce the evolution of massive galaxies, over the entire redshift range that we consider. However, lower mass galaxies are formed too early in the models and are too passive at late times. Thus, the models do not correctly reproduce the DS trend in stellar mass or the archaeological DS, while they qualitatively reproduce the mass-dependent evolution of the SFR. We demonstrate that these discrepancies are not solely due to a poor treatment of satellite galaxies but are mainly connected to the excessively efficient formation of central galaxies in high-redshift haloes with circular velocities ~100-200 km/s. [abridged]
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