以TeV伽马射线晕研究银河系宇宙线传播

宇宙线在银河系中的传播是宇宙线物理中最重要的研究内容之一，通常由扩散模型来描述。然而，作为目前限制宇宙线传播最主要的观测量，硼、碳流量之比仅能限制宇宙线在银河系中的平均扩散系数，对于扩散系数在银河系中如何分布则没有直接的观测证据。本课题拟利用TeV伽马射线晕作为观测量，研究银河系宇宙线传播的空间依赖。TeV伽马射线晕由中年脉冲星释放的电子在星际介质中扩散时通过逆康普顿散射产生，其形态是宇宙线扩散系数的直接测量。我们可以利用对TeV晕扩散系数的统计来分析扩散系数的空间分布。此外，我们也计划利用TeV晕检验扩散模型以外的宇宙线传播机制，如超扩散模型。我们对TeV晕的研究将基于LHAASO的观测结果。LHAASO以其前所未有的能量范围和灵敏度，能够为我们提供最理想的观测样本。

Cosmic-ray (CR) propagation is one of the major topics of CR researches. The Galactic propagation of CRs are generally believed to be a diffusion process. At present, the carbon-to-boron flux ratio is the most important quantity to measure the diffusion coefficient of CRs. However, it can only constrain the average diffusion coefficient in the Galaxy. We have little knowledge about the spatial distribution of the diffusion coefficient. In this project, we plan to use TeV gamma-ray halos as a probe to study the spatial dependency of CR propagation. TeV halos are generated by electrons escaping from middle-aged pulsars through inverse Compton scattering, the morphologies of which indicate the diffusion coefficient in the interstellar medium. The statistics of the TeV halos may indicate the spatial dependency of the diffusion coefficient. Moreover, we plan to test propagation models beyond the diffusion picture with the TeV halos, such as superdiffusion model. Our study will be based on the LHAASO experiment. With its unprecedentedly broad energy range and high sensitivity, LHAASO can provide us the best objects of study.