我们考虑的影响与详细的辐射转移在宇宙复合的时代对我们的宇宙电离历史。我们集中在氢莱曼-α共振在红移600<~ z <~ 2000的光子逃逸，这是定义宇宙复合速率的两个关键机制之一。我们在标准公式中处理这个问题，由于双光子相互作用的校正推迟到另一篇论文。作为主要结果，我们在这里表明，在非定常方法中，在红移800<~z<~1200范围内，对自由电子分数N_e的修正约为~1.6-1.8%.因此，所讨论的过程中的电离历史的最大修改之一，接近最大的埃里克森可见度函数在z~1100考虑到目前为止。我们证明了我们的结果，数值和分析，导出逃逸概率，并考虑莱曼α线发射和线吸收的方式不同的索伯列夫近似。特别是，我们给出了一个详细的推导过程中的氢复合的Sobolev逃逸概率，并解释了基本的假设。然后，我们讨论的情况下，相干散射的实验室框架中的光子逃逸，解决这个问题的解析在准静态近似，也在时间依赖的情况下。本文指出，在DP/P~5- 10%的水平上，氢复合过程中逃逸几率的Sobolev近似是不成立的。这是因为在复合过程中，电离度在特征时间Dz/z~ 10%内显著变化，使得在百分比水平精度下，光子分布不会演变（删节）。
英文摘要：
We consider the effects connected with the detailed radiative transfer during the epoch of cosmological recombination on the ionization history of our Universe. We focus on the escape of photons from the hydrogen Lyman-alpha resonance at redshifts 600<~ z <~ 2000, one of two key mechanisms defining the rate of cosmological recombination. We approach this problem within the standard formulation, and corrections due to two-photon interactions are deferred to another paper. As a main result we show here that within a non-stationary approach to the escape problem, the resulting correction in the free electron fraction, N_e, is about ~1.6-1.8% in the redshift range 800<~z<~1200. Therefore the discussed process results in one of the largest modifications to the ionization history close to the maximum of Thomson-visibility function at z~1100 considered so far. We prove our results both numerically and analytically, deriving the escape probability, and considering both Lyman-alpha line emission and line absorption in a way different from the Sobolev approximation. In particular, we give a detailed derivation of the Sobolev escape probability during hydrogen recombination, and explain the underlying assumptions. We then discuss the escape of photons for the case of coherent scattering in the lab frame, solving this problem analytically in the quasi-stationary approximation and also in the time-dependent case. We show here that during hydrogen recombination the Sobolev approximation for the escape probability is not valid at the level of DP/P~5-10%. This is because during recombination the ionization degree changes significantly over a characteristic time Dz/z~10%, so that at percent level accuracy the photon distribution is not evolving (abridged)
We investigate the effects of neutrino heating and alpha-particle recombination on the hydrodynamics of core-collapse supernovae. Our focus is on the non-linear dynamics of the shock wave that forms in the collapse, and the assembly of positive energy material below it. To this end, we perform time-dependent hydrodynamic simulations with FLASH2.5 in spherical and axial symmetry. These generalize our previous calculations by allowing for bulk neutrino heating and for nuclear statistical equilibrium between n, p and alpha. The heating rate is freely tunable, as is the starting radius of the shoc…
We study the properties of Lyman-alpha emitters (LAEs) and Lyman-break galaxies (LBGs) at z=3-6 using cosmological SPH simulations. We investigate two simple scenarios for explaining the observed Ly-a and rest-frame UV luminosity functions (LFs) of LAEs: (i) the "escape fraction" scenario, in which the "effective" escape fraction (including the IGM attenuation) of Ly-a photons is f_Lya ~0.1 (0.15) at z=3 (6), and (ii) the "stochastic" scenario, in which the fraction of LAEs that are turned on at z=3 (6) is \Cstoc ~0.07 (0.2) after correcting for the IGM attenuation. Our comparisons with a numb…
New HST Observations of the Halo Gas of NGC 3067: Limits on the Extragalactic Ionizing Background at Low Redshift and the Lyman Continuum Escape Fraction
