论文标题
HYREC-2：高度准确的子毫秒重组代码
HYREC-2: a highly accurate sub-millisecond recombination code
论文作者
论文摘要
我们介绍了新的重组代码HYREC-2，其准确性与最先进的代码HYREC和COSMOREC相同，同时超过了CMB-动脉底层数据分析的代码RECFAST的计算速度。 HYREC-2基于有效的4级原子模型，完全计入了高度激发氢的非平衡状态，并且非常准确地用于辐射转移效应，并校正了Lyman-$α$逃生率。后者是用原始HYREC计算的，并将其作为温度的函数以及相对于相关的宇宙参数而定。这使得代码能够保持与原始的HyRec-2相同的准确性，而Planck当前允许的宇宙学参数的整个99.7％置信区域，而在标准笔记本电脑上以一毫秒的速度运行。即使理想的宇宙变量有限实验最高$ \ ell $ = 5000，我们的代码也不会引起任何宇宙学参数的明显偏见。除了CMB各向异性计算之外，HYREC-2将是一个有用的工具，可以用于依赖重新组合和热历史的各种观察力，例如重新组合和热历史记录，例如重新组合或21-CM 21-CM 21-CM。
We present the new recombination code HYREC-2, holding the same accuracy as the state-of-the-art codes HYREC and COSMOREC and, at the same time, surpassing the computational speed of the code RECFAST commonly used for CMB-anisotropy data analyses. HYREC-2 is based on an effective 4-level atom model, accounting exactly for the non-equilibrium of highly excited states of hydrogen, and very accurately for radiative transfer effects with a correction to the Lyman-$α$ escape rate. The latter is computed with the original HYREC, and tabulated, as a function of temperature, along with its derivatives with respect to the relevant cosmological parameters. This enables the code to keep the same accuracy as the original HYREC-2 over the full 99.7% confidence region of cosmological parameters currently allowed by Planck, while running in under one millisecond on a standard laptop. Our code leads to no noticeable bias in any cosmological parameters even in the case of an ideal cosmic-variance limited experiment up to $\ell$ = 5000. Beyond CMB anisotropy calculations, HYREC-2 will be a useful tool to compute various observables that depend on the recombination and thermal history, such as the recombination spectrum or the 21-cm signal.
