GECO：星系演化代码--一个新的星系形成的半解析模型
GECO: Galaxy Evolution COde - A new semi-analytical model of galaxy formation
摘要：
我们提出了一个新的半解析模型的星系形成，GECO（星系演化代码），旨在更好地了解何时以及如何两个过程的恒星形成和星系组装已经发生。我们的模型被构造成一个基于扩展的Press-Schechter理论的MonteCarlo算法，用于描述暗物质晕的合并层次，以及一组用于处理重子物理的解析算法，包括气体冷却的经典配方，恒星形成的时间尺度，星系合并和SN反馈。与星系一起，BH的平行增长是在时间上进行的，并模拟了它们对宿主星系的反馈。我们设置的模型自由参数匹配的数据本地恒星质量函数和BH-膨胀关系在z=0。基于这样的局部边界条件，我们调查高红移宇宙的数据如何限制我们对驱动演化的物理过程的理解，特别关注恒星质量的组装和恒星形成的历史。由于这两个过程是目前强烈约束宇宙学的近红外和远红外调查，基本物理的λ CDM层次聚类概念的星系形成可以有效地测试我们通过比较与最可靠的一组观测。我们的研究表明，当研究恒星形成和质量组装的时间尺度作为暗物质晕质量和单个星系恒星质量的函数时，恒星形成的“缩小”方式似乎是模型的自然结果，即使在没有活动星系核反馈的情况下也能重现。相反，恒星的质量组装历史在宇宙时间中遵循一个更标准的等级模式，更大质量的系统在晚期主要通过无耗散合并组装。
英文摘要：
We present a new semi-analytical model of galaxy formation, GECO (Galaxy Evolution COde), aimed at a better understanding of when and how the two processes of star formation and galaxy assembly have taken place. Our model is structured into a Monte Carlo algorithm based on the Extended Press-Schechter theory, for the representation of the merging hierarchy of dark matter halos, and a set of analytic algorithms for the treatment of the baryonic physics, including classical recipes for the gas cooling, the star formation time-scales, galaxy mergers and SN feedback. Together with the galaxies, the parallel growth of BHs is followed in time and their feedback on the hosting galaxies is modelled. We set the model free parameters by matching with data on local stellar mass functions and the BH-bulge relation at z=0. Based on such local boundary conditions, we investigate how data on the high-redshift universe constrain our understanding of the physical processes driving the evolution, focusing in particular on the assembly of stellar mass and on the star formation history. Since both processes are currently strongly constrained by cosmological near- and far-IR surveys, the basic physics of the Lambda CDM hierarchical clustering concept of galaxy formation can be effectively tested by us by comparison with the most reliable set of observables. Our investigation shows that when the time-scales of the stellar formation and mass assembly are studied as a function of dark matter halo mass and the single galaxy stellar mass, the 'downsizing' fashion of star formation appears to be a natural outcome of the model, reproduced even in the absence of the AGN feedback. On the contrary, the stellar mass assembly history turns out to follow a more standard hierarchical pattern progressive in cosmic time, with the more massive systems assembled at late times mainly through dissipationless mergers.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
