21CMMC: an MCMC analysis tool enabling astrophysical parameter studies of the cosmic 21 cm signal
21CMMC: an MCMC analysis tool enabling astrophysical parameter studies of the cosmic 21 cm signal
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DOI：
10.1093/mnras/stv571
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发表时间：
2015-01
影响因子：
4.8
通讯作者：
B. Greig;A. Mesinger
中科院分区：
文献类型：
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作者：
B. Greig;A. Mesinger
我们介绍21 CMMC：一个并行化的蒙特卡罗马尔可夫链分析工具，结合了再电离（EoR）的时间的数值模拟21 CMFAST。21 CMMC估计天体物理参数约束从21厘米EoR实验，容纳各种EoR模型，以及先验模型参数和再电离历史。为了说明它的效用，我们考虑两种不同的EoR方案，一个是一个单一的人口的星系（与质量无关的电离效率）和第二个，更一般的模型与两个不同的，反馈调节的人口（每个与质量相关的电离效率）。作为一个例子，结合三个观察（z=8，9和10）的21厘米功率谱与保守的噪声估计和均匀的模型先验，我们发现，干涉仪的规格，如低频阵列/氢时代的再电离阵列（HERA）/平方公里阵列1（SKA 1）可以约束常见的再电离参数：电离效率（或类似的逃逸分数），电离光子的平均自由程和恒星形成晕的最低维里温度的对数在45.3/22.0/16.7以内，分别为33.5/18.4/17.8和6.3/3.3/2.4%，~ 1\sigma $分数不确定度。相反，如果我们乐观地假设，我们可以完美地描述EoR建模的不确定性，我们可以改善这些约束的一个因素~几。同样，对于HERA和SKA 1，平均中性分数的分数不确定性可被限制在$\lesssim10$ %以内。通过研究由此产生的对天体物理约束的影响，21 CMMC可用于优化（i）干涉仪设计;（ii）前景清理算法;（iii）观测策略;（iv）表征21 cm信号的替代统计数据;以及（v）与其他观测计划的协同作用。
We introduce 21CMMC: a parallelized, Monte Carlo Markov Chain analysis tool, incorporating the epoch of reionization (EoR) seminumerical simulation 21CMFAST. 21CMMC estimates astrophysical parameter constraints from 21 cm EoR experiments, accommodating a variety of EoR models, as well as priors on model parameters and the reionization history. To illustrate its utility, we consider two different EoR scenarios, one with a single population of galaxies (with a mass-independent ionizing efficiency) and a second, more general model with two different, feedback-regulated populations (each with mass-dependent ionizing efficiencies). As an example, combining three observations (z=8, 9 and 10) of the 21 cm power spectrum with a conservative noise estimate and uniform model priors, we find that interferometers with specifications like the Low Frequency Array/Hydrogen Epoch of Reionization Array (HERA)/Square Kilometre Array 1 (SKA1) can constrain common reionization parameters: the ionizing efficiency (or similarly the escape fraction), the mean free path of ionizing photons and the log of the minimum virial temperature of star-forming haloes to within 45.3/22.0/16.7, 33.5/18.4/17.8 and 6.3/3.3/2.4 per cent, ~$1\sigma$ fractional uncertainty, respectively. Instead, if we optimistically assume that we can perfectly characterize the EoR modelling uncertainties, we can improve on these constraints by up to a factor of ~few. Similarly, the fractional uncertainty on the average neutral fraction can be constrained to within $\lesssim10$ per cent for HERA and SKA1. By studying the resulting impact on astrophysical constraints, 21CMMC can be used to optimize (i) interferometer designs; (ii) foreground cleaning algorithms; (iii) observing strategies; (iv) alternative statistics characterizing the 21 cm signal; and (v) synergies with other observational programs.