1. Beijing Institute of Spacecraft Environment Engineering, Beijing 100094;2. National Key Laboratory of Science and Technology on Reliability and Environmental Engineering, Beijing 100094;3. Department of Engineering Physics, Tsinghua University, Beijing 100084;4. Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084;
伽马射线作为宇宙中极端事件的独特探针, 探测伽马射线是人们了解宇宙构成、星体演化和宇宙线起源等的重要途经. 伽马天文涉及了宇宙中的各种前沿科学问题并且观测所需能谱跨度极宽($10^2$keV--$10^2$TeV), 针对不同的科学目标和细分谱段, 必须利用不同的伽马望远镜探测技术. 总结了空间和地面的共5大类伽马射线观测技术, 分别是编码孔径望远镜、康普顿望远镜、电子对望远镜、成像大气切伦科夫望远镜和广延大气簇射阵列; 回顾了70 yr来在观测设备和技术进步的推动下伽马射线天文学领域的巨大进展, 其中包含高能和甚高能谱段取得的大量成就, 中低能段由于已有观测任务有限以及灵敏度低, 超高能和极高能段由于观测难度大、起步时间晚, 数据和成果相对其他谱段产出较少; 展望了未来已经规划的伽马望远镜任务、能力及预期科学产出, 其中, 中低能段空间望远镜增强型ASTROGAM望远镜(e-ASTROGAM)、全天区中能伽马射线观测站 (AMEGO)和甚高能段地面望远镜阵列高海拔宇宙线观测站(LHAASO)、 切伦科夫望远镜阵列(CTA), 由于灵敏度较同谱段已有任务灵敏度有大幅提升, 极有可能在20 yr内从不同角度再度扩展人类对伽马宇宙的认知.
gamma-rays are a unique probe for extreme events in the universe. Detecting the gamma-rays provides an important opportunity to understand the composition of universe, the evolution of stars, the origin of cosmic rays, etc. gamma-ray astrophysics involves in various frontier scientific issues, and the observed energy spectrum spans over a wide range from a few hundreds of keV to a few hundreds of TeV. Different gamma-ray telescopes are in need for the different scientific goals and spectral bands. In this work, 5 kinds of space- and ground-based gamma-ray observing techniques were summarized including the Coded-aperture telescopes, Compton telescopes, pair-production telescopes, Imaging Atmospheric Cherenkov Telescopes, and Extensive Air Shower Arrays. The progress in gamma-ray astrophysics in the past 70 years, motivated by the observation capability, was reviewed. Great achievements have been made in the high-energy band and very-high-energy band, while because of the limited missions conducted, as well as a lower sensitivity comparing with other bands, discoveries in low- and medium-energy are few, and due to the high observation difficulty, as well as the late start, relevant scientific yields in ultra- and extremely-high energy are limited. Moreover, the future planned missions and capabilities of the gamma-ray telescopes and their possible scientific outputs were discussed. Among these missions, low- and medium-energy space telescopes e-ASTROGAM (enhanced-ASTROGAM), AMEGO (All-sky Medium Energy Gamma-ray Observatory), and very-high-energy ground-based arrays LHAASO (Large High Altitude Air Shower Observatory), CTA (Cherenkov Telescope Array) greatly improve sensitivity than their corresponding last generation, thus expect very likely to further expand our knowledge on the gamma-universe.