星系形成的半解析模型研究进展

Progress on the Semi-Analytical Model of Galaxy Formation

基于目前流行的冷暗物质等级成团理论的星系形成的半解析模型取得了很大进展。在引入一系列合理的关于重子物质物理过程的假设,如气体冷却、恒星形成率、超新星能量反馈以后, 结合N体数值模拟,星系形成的半解析模型一方面能较成功地预言许多与观测符合的近邻星系的性质,如光度函数、星系的两点相关函数、Tully-Fisher关系、星系团中椭圆星系的颜色-星等关系等;另一方面还能较成功地预言宇宙的恒星形成历史,以及一部分高红移星系的性质,如Lyman-Break星系的数目随红移的分布。但是最近一些观测表明,半解析模型在高红移预言的大质量星系较少,且红星系数目也较观测少。重点讨论半解析模型成功与不足之处,并指出解决这些问题可能的途径。

Based on the current popular hierarchical clustering model of Cold Dark Matter (CDM), The Semi-Anlytical Model (SAM) of galaxy formation have made impressive progress. After introducing the reasonable prescription about the baryonic process, such as the gas cooling, star formation, energy feedback from supernova and AGN, the SAM succeeds in predicting many observations. On one hand, SAM can match the observations of local galaxy population, which include the luminosity function, the two-point correlation function, Tully-Fisher relation, the color-magnitude relation. On the other hand, SAM also match observations of high-redshift universe, such as the cosmic star formation history, and the redshift-distribution of Layman-Break galaxies. But some recent evidence implies that SAM redicts less massive galaxies at high redshift, and insufficient number of extrely red objects. In this review, we discuss the success and failure of SAM, and give hint on how to improve the SAM.