标题： 用强莱曼α发射的莱曼断裂星系在5 < z < 7之间的比例建模 显示英文标题

标题： Modelling the fraction of Lyman Break Galaxies with strong Lyman alpha emission at 5 < z < 7

摘要： 我们提出了理论结果，说明在红移范围5 < z < 7内，Lyman Break星系（LBGs）被检测为强Lyman alpha发射体（LAEs）的期望比例。我们的分析基于20亿粒子的SPH模拟MareNostrum高红移宇宙。我们将星系近似为静态的尘埃板，并且额外的团状尘埃分布影响年龄小于25 Myr的恒星种群。Lyman alpha逃逸分数的模型基于我们蒙特卡洛辐射转移代码（CLARA）对于板状结构的结果。我们还固定Lyman alpha光子通过星际介质的传输率为50%在所有红移下。从该模型的结果中，我们计算xLya，即Lyman alpha等值宽度（EW）大于50埃的Lyman Break星系的比例。我们在4.5 < z < 6范围内发现与观测数据惊人的一致性。对于明亮（-22 < MUV < -20.5）和暗淡（-20.5 < MUV < -18.5）星系，我们的模型预测xLya = 0.02\pm 0.01和xLya = 0.47\pm 0.01，而观测者报告的xLya分别为0.08\pm 0.02和0.47\pm 0.16。在红移z\sim 7时，消光模型的额外演化减少了透射Lyman alpha辐射的强度，因子为f_T = 0.4以匹配z\sim 6.5时的LAE光度函数，自然提供了对z > 6.3最近报告的xLya比例的良好匹配。探索不同的Lyman alpha逃逸分数玩具模型，我们表明随着紫外星系光度增加，Lyman alpha逃逸分数减少是我们的模型中解释较暗LBGs具有较大xLya比例的关键因素。 显示英文摘要

摘要： We present theoretical results for the expected fraction of Lyman Break Galaxies (LBGs) to be detected as strong Lyman alpha emitters (LAEs) in the redshift range 5 < z < 7. We base our analysis on the 2-billion particle SPH simulation MareNostrum High-z Universe. We approximate galaxies as static dusty slabs with an additional clumpy dust distribution affecting stellar populations younger than 25 Myr. The model for the Lyman alpha escape fraction is based on the results of our Monte-Carlo radiative transfer code (CLARA) for a slab configuration. We also fix the transmission of Lyman alpha photons through the intergalactic medium to a constant value of 50% at all redshifts. From the results of this model we calculate xLya, the fraction of Lyman Break Galaxies with Lyman alpha equivalent width (EW) larger than 50 Angstrom. We find a remarkable agreement with observational data at 4.5 < z < 6. For bright (-22 < MUV < -20.5) and faint (-20.5 < MUV < -18.5) galaxies our model predicts xLya = 0.02 \pm 0.01 and xLya = 0.47 \pm 0.01 while observers report xLya = 0.08 \pm 0.02 and xLya = 0.47 \pm 0.16, respectively. Additional evolution of the extinction model at redshift z \sim 7, that decreases the intensity of transmitted Lyman alpha radiation by a factor of f_T = 0.4 as to match the LAE luminosity function at z \sim 6.5, naturally provides a good match for the recently reported xLya fractions at z > 6.3. Exploring different toy models for the Lyman alpha escape fraction, we show that a decreasing Lyman alpha escape fraction with increasing UV galaxy luminosity is a key element in our model to explain the of larger xLya fractions for fainter LBGs.