星系形成与演化半解析理论研究的新进展

Investigation in the Semi-Analytic Theory for Galaxy Formation and Evolution

发展了的星系形成和演化的半解析理论，可以很好地再现不同红移时宇宙恒星形成率密度（ＳＦＲ）和中性气体共动密度的最新观测结果。对该理论各个不确定性因素对结果的影响作了详尽的讨论，并指出在中等红移星系间的相互作用可能是主宰恒星形成的决定性因素。根据宇宙学模型对观测和半解析理论的影响，对宇宙学参数作出限制。

In this paper the popular semi-analytic models for galaxy formation and evolution under the hierarchical scenario are discussed, based on the most recently observed cosmic star formation history. The standard treatment as well as individual departures are studied. The results can be described as follows. There seems to be no challenge to the present theories of galaxy formation and evolution. Departures of the density profile of halo, SN feedback process and metallicity are important in the modeled calculations, but those of the halo spin parameter, of the adopted range for the circular velocity and of the relation between disk size and its mother halo's vinal and/or cooling radius, do not have significant influences. Merger between galaxies should be dominant and responsible to the deviation of the theoretical results from observed ones at intermediate redshift, which implies that most of spherical objects should form between redshift 0.5 and 1.5 with the age of some 8Gyr that is cosmology dependent. Furthermore, the predicted cosmic evolution of the cold gas component is fairly consistent with observations. Finally, the constraint of cosmological parameters are suggested, which is consistent with those obtained from other methods.