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arXiv 1711.03416astro-ph.GA
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宇宙恒星的形成:SFRD(z)的一个简单模型

Cosmic Star Formation: a simple model of the SFRD(z)

Cesare Chiosi, Mauro Sciarratta, Mauro D'Onofrio, Emanuela Chiosi, Francesca Brotto, Rosaria De Michele, Valeria Politino

摘要:

我们研究了宇宙恒星形成率密度(SFRD)从红移z=20到z=0的演化,并将其与Madau和Dickinson从最近的紫外和红外数据汇编中得到的观测值进行了比较。理论SFRD(z)及其演化是利用一个简单的模型得到的,该模型将代表不同形态类型的真实天体的原型星系的恒星形成历史和Λ-CDM宇宙演化中从小扰动到大尺度天体在引力作用下的结构层次生长叠加在一起,即暗物质晕的数密度N(M,z).虽然整体模型是非常简单和容易建立,它提供的结果,以及模仿从大规模N体模拟的非常复杂。我们的方法的简单性,使我们能够测试不同的假设在星系中的恒星形成规律,从恒星到星际气体的能量反馈的影响和星系风的效率,以及N(M,z)的效果。我们的分析结果是,在星系分级集合的框架下,在能量反馈和星系风的简单假设下,所谓的延迟恒星形成可以再现观测到的SFRD(z)。

英文摘要:

We investigate the evolution of the cosmic star formation rate density (SFRD) from redshift z=20 to z=0 and compare it with the observational one by Madau and Dickinson derived from recent compilations of UV and IR data. The theoretical SFRD(z) and its evolution are obtained using a simple model which folds together the star formation histories of prototype galaxies designed to represent real objects of different morphological type along the Hubble sequence and the hierarchical growing of structures under the action of gravity from small perturbations to large scale objects in Λ-CDM cosmogony, i.e. the number density of dark matter halos N(M,z). Although the overall model is very simple and easy to set up, it provides results that well mimic those obtained from large scale N-body simulations of great complexity. The simplicity of our approach allows us to test different assumptions for the star formation law in galaxies, the effects of energy feedback from stars to interstellar gas and the efficiency of galactic winds, and also the effect of N(M,z). The result of our analysis is that in the framework of the hierarchical assembly of galaxies the so-called time-delayed star formation under plain assumptions mainly for the energy feedback and galactic winds can reproduce the observational SFRD(z).

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