Semi-numerical simulation of reionization with semi-analytical modeling of galaxy formation  

作　　者：Jie Zhou Qi Guo Gao-Chao Liu Bin Yue Yi-Dong Xu Xue-Lei Chen 

机构地区：[1]National Astronomical Observatories,Chinese Academy of Sciences [2]College of Science,China Three Gorges University [3]Center of High Energy Physics,Peking University

出　　处：《Research in Astronomy and Astrophysics》2013年第4期373-386,共14页天文和天体物理学研究（英文版）

基　　金：supported by the MOST 863 Project (No. 2012AA121701);the National Natural Science Foundation of China (Grant No. 11073024);CAS grant KJCX2-EW-W01;the John Templeton Foundation

摘　　要：In a semi-numerical model of reionization, the evolution of ionization fraction is approximately simulated by the criterion of ionizing photon to baryon ratio. We incorporate a semi-analytical model of galaxy formation based on the Millennium II N-body simulation into the semi-numerical modeling of reionization. The semianalytical model is used to predict the production of ionizing photons, then we use the semi-numerical method to model the reionization process. Such an approach allows more detailed modeling of the reionization, and also connects observations of galaxies at low and high redshifts to the reionization history. The galaxy formation model we use was designed to match the low-z observations, and it also fits the high redshift luminosity function reasonably well, but its prediction about star formation falls below the observed value, and we find that it also underpredicts the stellar ionizing photon production rate, hence the reionization cannot be completed at z ~ 6. We also consider simple modifications of the model with more top heavy initial mass functions, which can allow the reionization to occur at earlier epochs. The incorporation of the semi-analytical model may also affect the topology of the HI regions during the epoch of reionization, and the neutral regions produced by our simulations with the semi-analytical model, which appeared less poriferous than the simple halo-based models.In a semi-numerical model of reionization, the evolution of ionization fraction is approximately simulated by the criterion of ionizing photon to baryon ratio. We incorporate a semi-analytical model of galaxy formation based on the Millennium II N-body simulation into the semi-numerical modeling of reionization. The semianalytical model is used to predict the production of ionizing photons, then we use the semi-numerical method to model the reionization process. Such an approach allows more detailed modeling of the reionization, and also connects observations of galaxies at low and high redshifts to the reionization history. The galaxy formation model we use was designed to match the low-z observations, and it also fits the high redshift luminosity function reasonably well, but its prediction about star formation falls below the observed value, and we find that it also underpredicts the stellar ionizing photon production rate, hence the reionization cannot be completed at z ~ 6. We also consider simple modifications of the model with more top heavy initial mass functions, which can allow the reionization to occur at earlier epochs. The incorporation of the semi-analytical model may also affect the topology of the HI regions during the epoch of reionization, and the neutral regions produced by our simulations with the semi-analytical model, which appeared less poriferous than the simple halo-based models.

关 键 词：cosmology reionization - galaxies formation 

分 类 号：P144[天文地球—天体物理]