Constraints on the spatially dependent cosmic-ray propagation model from Bayesian analysis,Physical Review D

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Constraints on the spatially dependent cosmic-ray propagation model from Bayesian analysis
Physical Review D ( IF 4.6 ) Pub Date : 2021-12-01 , DOI: 10.1103/physrevd.104.123001
Meng-Jie Zhao _{1,

2} , Kun Fang ₁ , Xiao-Jun Bi _{1,

2}

Affiliation

The energy spectra of primary and secondary cosmic rays (CRs) generally harden at several hundreds of GeV, a finding which can be naturally interpreted by means of propagation effects. We adopt a spatially dependent CR propagation model to fit the spectral hardening, where a slow-diffusion disk (SDD) is assumed near the galactic plane. We aim to constrain the propagation parameters with a Bayesian parameter estimation based on a Markov chain Monte Carlo sampling algorithm. The latest precise measurements of carbon spectrum and B/C ratio are adopted in the Bayesian analysis. The

{}^{10}{Be} / {}^{9}{Be}

and Be/B ratios are also included to break parameter degeneracies. The fitting result shows that all the parameters are well constrained. Especially, the thickness of the SDD is limited to 0.4–0.5 kpc above and below the galactic plane, which could be the best constraint for the slow-diffusion region among similar works. The

\bar{p} / p

ratio and the amplitude of CR anisotropy predicted by the SDD model are consistent with the observations, while the predicted high-energy electron and positron fluxes are slightly and significantly lower than the observations, respectively, indicating the necessity of extra sources.

中文翻译：

贝叶斯分析对空间相关宇宙射线传播模型的约束

一次和二次宇宙射线 (CR) 的能谱通常在数百 GeV 时硬化，这一发现可以通过传播效应自然地解释。我们采用空间相关的 CR 传播模型来拟合光谱硬化，其中假设在银河平面附近有一个慢扩散盘 (SDD)。我们旨在通过基于马尔可夫链蒙特卡罗采样算法的贝叶斯参数估计来约束传播参数。贝叶斯分析采用最新的碳谱和B/C比的精确测量。这