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首页> 外文期刊>The Astrophysical Journal. Letters >On the lack of evolution in galaxy star formation efficiency
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On the lack of evolution in galaxy star formation efficiency

机译：关于缺乏演化的星系恒星形成效率

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摘要

Using reconstructed galaxy star formation histories, we calculate the instantaneous efficiency of galaxy star formation (i.e., the star formation rate divided by the baryon accretion rate) from z = 8 to the present day. This efficiency exhibits a clear peak near a characteristic halo mass of 10 ~(11.7) M_⊙, which coincides with longstanding theoretical predictions for the mass scale relevant to virial shock heating of accreted gas. Above the characteristic halo mass, the efficiency falls off as the mass to the minus four-thirds power; below the characteristic mass, the efficiency falls off at an average scaling of mass to the two-thirds power. By comparison, the shape and normalization of the efficiency change very little since z = 4. We show that a time-independent star formation efficiency simply explains the shape of the cosmic star formation rate since z = 4 in terms of dark matter accretion rates. The rise in the cosmic star formation from early times until z = 2 is especially sensitive to galaxy formation efficiency. The mass dependence of the efficiency strongly limits where most star formation occurs, with the result that two-thirds of all star formation has occurred inside halos within a factor of three of the characteristic mass, a range that includes the mass of the Milky Way.
机译：使用重建的星系恒星形成历史，我们计算了从z = 8到现在的星系恒星形成的瞬时效率（即，恒星形成率除以重子吸积率）。该效率在特征光晕质量10〜（11.7）M_⊙附近表现出一个清晰的峰值，这与对与吸积气体的病毒冲击加热有关的质量规模的长期理论预测相吻合。在特征光晕质量以上，效率随质量下降到负三分之四而下降;低于特性质量，效率在质量平均缩放到三分之二的功率时下降。相比之下，自z = 4以来，效率的形状和归一化变化很小。我们表明，与时间无关的恒星形成效率简单地解释了自z = 4以来暗物质累积率方面的宇宙恒星形成率的形状。从早期到z = 2的宇宙恒星形成的上升对星系形成效率特别敏感。效率的质量依赖性极大地限制了大多数恒星形成的位置，结果，所有恒星形成的三分之二都发生在晕圈内，其质量为特征质量的三分之一，该范围包括银河系的质量。

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