超高能宇宙线从何而来？  

Where do the ultra-high energy cosmic rays come from?

作　　者：胡红波[1,2] 王祥玉 刘四明[4,5] Hongbo Hu;Xiangyu Wang;Siming Liu(Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;School of Astronomy and Space Science,Nanjing University,Nanjing 210023,China;Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210034,China;School of Astronomy and Space Sciences,University of Science and Technology,Hefei 230026,China)

机构地区：[1]中国科学院高能物理研究院,北京100049 [2]中国科学院大学物理科学学院,北京100049 [3]南京大学天文与空间科学学院,南京210023 [4]中国科学院紫金山天文台,南京210034 [5]中国科技大学天文和空间科学学院,合肥230026

出　　处：《科学通报》2018年第24期2440-2449,共10页Chinese Science Bulletin

摘　　要：宇宙线是来自外太空的唯一物质样本,携带着粒子物理、高能天体物理、宇宙物质组成及其演化的丰富信息.已知的宇宙线粒子最高能量约为3×10^(20) eV."宇宙线是如何被加速的?""其起源天体是什么?""在这样的高能情况下,已知的物理学规律是否还能适用?"等这些都是有待解决的重大科学问题.为此人们通过多种实验手段在空间和地上开展宇宙线的多信使研究.在过去的几十年里,宇宙线、伽马射线和中微子观测取得了丰富的成果:(1)宇宙线能谱、成分和各向异性的测量精度达到了史无前例的水平,极高能宇宙线的偶极各向异性表明这些粒子来自银河系之外;(2)空间实验发现了3000多个GeV伽马源,地面实验发现了近200个TeV源,它们大多为高能电子源,有几个已被认证为强子源;(3)冰立方实验发现了近百个高能中微子,它们的各向同性分布暗示着河外起源.这些新结果为解决宇宙线的起源问题和发展相关的粒子加速理论奠定了基础.新一代更高灵敏度的实验装置的建设和运行正在开启宇宙线粒子天体物理研究的新篇章.Cosmic rays are the only sample of matter coming from outer space. They carry rich information about particle physics, high-energy astrophysics, composition and evolution of the Universe. The highest energy of cosmic rays detected so far is about 3×1020 eV. ＂How are the cosmic rays accelerated？＂＂What kind of astronomic sources do the cosmic rays originate from？＂＂Are the fundamental physics laws still valid in such high-energy scales？＂ are all important scientific problems waiting to be addressed. To answer these questions, various space and ground experiments have been carried out to explore the nature of cosmic rays in a multi-messenger approach. The past few decades have witnessed great achievements in high-energy cosmic ray, gamma ray, neutrino observations, and detection of gravitational wave. （1） The cosmic ray spectra, composition, and anisotropy have been measured with unprecedented precision leading to better understanding of cosmic ray acceleration and transport and stricter constraints on properties of potential candidates of dark matter particles, and the dipole anisotropy of ultrahigh energy cosmic rays indicates that they have an extragalactic origin. （2） Space borne experiments have discovered more than 3000 sources in the GeV range, and the ground based experiments have uncovered more than 200 sources at TeV energies. Most of these sources are high-energy electron accelerators, and a few of them are identified as the accelerators of cosmic ray nuclei. Diffuse gamma-ray emission associated with galactic disks and jets and/or outbursts of Active Galactic Nuclei is also measured with better spatial and energy resolutions, which can be used to study cosmic ray transport in the interstellar/galactic/cluster medium. （3） With the IceCube experiment, about 100 high-energy neutrino events have been recorded and their isotropic distribution suggests an extragalactic origin. （4） The first gravitational wave event with simultaneous multi-wavelength observations has been detec

关 键 词：宇宙线 伽马射线 高能中微子 激波加速 多信使 

分 类 号：P172.4[天文地球—天文学]