科研之友
微信
新浪微博
Facebook
分享链接
摘要
We present theoretical predictions of the UV continuum luminosity UV LF) and Ly alpha equivalent width (EW) distribution of Ly alpha emitters (LAEs) in the framework of the hierarchical clustering model of galaxy formation. The model parameters for the LAEs were determined by fitting to the observed Ly alpha LF at z = 5.7 in our previous study, and the fit indicates that extinction of Ly alpha photons by dust is significantly less effective than that of UV continuum photons, implying a clumpy dust distribution in the interstellar medium. We then compare the predictions about UV LFs and EW distributions with a variety of observations at z similar to 3-6, allowing no more free parameters and paying careful attention to the selection conditions of LAEs in each survey. We find that the predicted UV LFs and EW distributions are in nice agreement with observed data, and especially, our model naturally reproduces the existence of large EW LAEs (greater than or similar to 240 angstrom) without introducing Pop III stars or top-heavy initial mass function. We show that both the stellar population (young age and low metallicity) and extinction by clumpy dust are the keys to reproducing large EW LAEs. The evidence of EW enhancement by clumpy dust is further strengthened by the quantitative agreement between our model and recent observations about a positive correlation between EW and extinction. The observed trend that brighter LAEs in the UV continuum tend to have smaller mean EW is also reproduced, and the clumpy dust plays an important role again for this trend. We suggested in our previous study that the transmission of the intergalactic medium for Ly alpha emission rapidly decreases from z similar to 6 to 7 by fitting to Ly alpha LFs, and this evidence is quantitatively strengthened by the comparison with the UV LF and EW distribution at z similar to 6.6.
- 出版日期2010-1-10
- 单位中国科学院国家天文台
