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HIGH-REDSHIFT GALAXIES IN COLD DARK MATTER MODELS

机译：冷暗物质模型中的高漂移星系

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We use hydrodynamic cosmological simulations to predict the star formation properties of high-redshift galaxies (z = 2-6) in five variants of the inflationary cold dark matter scenario, paying particular attention to z = 3, the redshift of the largest " Lyman break galaxy " (LBG) samples. Because we link the star formation timescale to the local gas density, the rate at which a galaxy forms stars is governed mainly by the rate at which it accretes cooled gas from the surrounding medium. At z = 3, star formation in most of the simulated galaxies is steady on ～200 Myr timescales, and the instantaneous star formation rate (SFR) is correlated with total stellar mass. However, there is enough scatter in this correlation that a sample selected above a given SFR threshold may contain galaxies with a fairly wide range of masses. The redshift history and global density of star formation in the simulations depend mainly on the amplitude of mass fluctuations in the underlying cosmological model. The three models whose mass fluctuation amplitudes agree with recent analyses of the Lyα forest also reproduce the observed luminosity function of LBGs reasonably well, although the dynamic range of the comparison is small and the theoretical and observational uncertainties are large. The models with higher and lower amplitudes appear to predict too much and too little star formation, respectively, although they are not clearly ruled out. The intermediate amplitude models predict SFR ～30-40 solar mass yr~(-1) for galaxies with a surface density of ～1 arcmin~(-2) per unit redshift at z = 3. They predict much higher surface densities at lower SFR, and significant numbers of galaxies with SFR > 10 solar mass yr~(-1) at z ≥ 5.
机译：我们使用流体力学宇宙学模拟来预测高通量红移星系（z = 2-6）在充气冷暗物质情景的五个变体中的恒星形成特性，尤其要注意z = 3，这是最大的“莱曼断裂”的红移星系”（LBG）样本。因为我们将恒星形成的时标与当地的气体密度联系在一起，所以星系形成恒星的速率主要取决于它从周围介质中吸收冷却气体的速率。在z = 3时，大多数模拟星系中的恒星形成都稳定在〜200 Myr时标上，并且瞬时恒星形成率（SFR）与总恒星质量相关。但是，这种相关性存在足够的分散性，以至于在给定的SFR阈值之上选择的样本可能包含质量范围相当广的星系。在模拟中，红移历史和恒星形成的整体密度主要取决于基本宇宙学模型中质量波动的幅度。尽管比较的动态范围很小并且理论和观测的不确定性很大，但三个质量波动幅度与Lyα森林最近的分析相吻合的模型也很好地再现了观测到的LBG的光度函数。尽管没有明确排除，具有较高和较低振幅的模型似乎分别预测了太多和太少的恒星形成。中间振幅模型预测了在z = 3时每单位红移的表面密度为〜1 arcmin〜（-2）的星系的SFR〜30-40太阳质量yr〜（-1）。他们预测了在较低的SFR时更高的表面密度，并且在z≥5时有大量SFR> 10太阳质量yr〜（-1）的星系。

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