共查询到19条相似文献，搜索用时 125 毫秒
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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(102 keV–102 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. 相似文献
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正近日,我国的重大科技基础设施"高海拔宇宙线观测站"(Large High Altitulde Air Shower Observatory, LHAASO)在《Nature》期刊上发表了首批科学结果[1]. LHAASO利用其1/2阵列在2020年1月至11月这段时期的数据,共发现了12个显著性大于7倍标准偏差的超高能伽马射线(指能量大于100 Te V的光子, 1 TeV=10~(12)eV)源. 相似文献
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宇宙线的观测研究和暗物质粒子的间接探测是高能天体物理领域两个重大研究课题. 自1912年V. Hess发现宇宙线开始, 人类对宇宙线的观测历史已经超过了一个世纪, 传统理论模型预言``膝''区以下能段的宇宙线能谱应服从单一幂率分布, 而近些年的空间和高空气球实验表明10 GeV--100 TeV的宇宙线质子能谱可能存在偏离单一幂律谱分布的重要结构, 这对研究银河系内宇宙线的起源、传播和加速机制具有重要意义. 另一方面, 得益于宇宙线和伽马射线观测精度的提高和观测能段的拓宽, 暗物质粒子的间接探测在国际上受到越来越多的关注, 暗物质粒子可能会发生湮灭或衰变产生稳定的普通高能粒子, 包括正负电子对、正反质子对、伽马射线和中微子等, 进而在宇宙线或伽马射线留下可探测的信号. 相似文献
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高能宇宙线的起源、加速和传播是重大的前沿科学问题,回答该问题需要对宇宙线的能谱、各向异性以及各类高能天体电磁辐射进行精确观测.通过空间粒子探测器对宇宙线各成分能谱的直接测量是研究宇宙线物理问题的重要手段.中国于2015年底发射并持续运行至今的暗物质粒子探测卫星以其大接受度、高能量分辨率等特点,在宇宙线直接探测方面取得了系列重要成果,揭示出质子、氦核、硼碳和硼氧比例等宇宙线能谱的新结构,为理解宇宙线起源等科学问题提供了新的依据.介绍了暗物质粒子探测卫星的仪器设置、运行状况、科学成果及其物理意义. 相似文献
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《天文学进展》2021,(1)
银河系外的伽马射线辐射源主要是耀变体,对其研究有助于揭示活动星系核喷流物理、高能宇宙线起源甚至宇宙演化等。研究了为什么有些蝎虎天体有强的伽马射线辐射,而有些却没有。选了170个有多普勒因子和能谱曲率测量的蝎虎天体,并把它们分成被费米LAT探测到的和未被费米LAT探测到的两类。研究发现这两类源的多波段能谱曲率有显著区别,即费米LAT探测到的源的曲率明显小于未被费米LAT探测到的源;即使扣除了多普勒因子的影响,结果也相近。蝎虎天体PKS 0048-09和S5 0716+714有着相似的同步辐射光度但却不同的伽马射线光度。基于同步自康普顿模型,再结合二次曲线电子谱可以很好地拟合它们的多波段能谱,并发现拟合的曲率和辐射区尺度不同但却成正比。PKS 0048-09可能有一个更致密的喷流,从而产生了更大康普顿因子。结果表明,给定同步辐射光度,能谱曲率和康普顿因子对于能否被Fermi伽马射线卫星探测到非常重要;讨论了这一结果对粒子统计加速和辐射机制的限制。 相似文献
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宇宙线发现100年来极大地推动了粒子物理学、天体物理学的发展,然而其起源、加速和传播的问题依然是宇宙线研究的三个根本问题。宇宙线“膝区”物理的研究是解决宇宙线这些基本问题的途径之一。简要回顾了宇宙线研究的历史和能谱特点;重点阐述了宇宙线“膝区”的实验观测数据以及重要实验组测量的差异和争论的焦点;归纳讨论了解释宇宙线“膝区”成因的四种主要理论模型,并结合最新实验数据说明了第四种成因(新物理过程)的可能性不大;叙述了国内研究者对宇宙线“膝区”物理研究的贡献;最后对宇宙线“膝区”物理研究的前景进行了展望。 相似文献
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宇宙线的起源是高能天体物理的核心问题之一.一直以来,超新星爆发被认为是能谱膝区以下宇宙线的主要来源.多波段观测表明,超新星遗迹有能力加速带电粒子至亚PeV (10~(15)eV)能量.扩散激波加速被认为是最有效的天体高能粒子加速机制之一,而超新星遗迹的大尺度激波正好为这一机制提供平台.近年来,一系列较高精度的地面和空间实验极大地推动了对宇宙线以及超新星遗迹的研究.新的观测事实挑战着传统的扩散激波加速模型以及其在银河系宇宙线超新星遗迹起源学说上的应用,深化了人们对宇宙高能现象的认识.结合超新星遗迹辐射能谱的时间演化特性,构建的时间依赖的超新星遗迹粒子加速模型,不仅能够解释200 GV附近宇宙线的能谱反常,还自然地形成能谱膝区,甚至可以将超新星遗迹粒子加速对宇宙线能谱的贡献延伸至踝区.该模型预期超新星遗迹中粒子的输运行为表现为湍流扩散,这需要未来的观测以及与粒子输运相关的等离子体数值模拟工作来进一步验证. 相似文献
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我国4300 m高度上的高能宇宙线研究 总被引：3，自引：0，他引：3
随着γ射线天文学的兴起，10年前在西藏高原海拔4300m的羊八井谷地，出现并成长着一个国际知名的宇宙线实验站。其中日合作的ASγ阵列在国际同类实验中，首先观测到了蟹状星云的Multi-TeV稳定γ射线发射及活动星系核Mrk 501在1997年、Mrk 421在2000年的Multi-TeVγ射线强爆发，独家测出了反映太阳和行星际磁场状态的宇宙线太阳阴影的偏移并将之用于太阳活动变化的监测，利用高海拔优势及乳胶室和Burst，探测器与阵列的联合实验进行了超高能宇宙线能谱和成分的研究。以高阻板探测器(RPC)地毯式阵列迈入≈100GeV空白能区的中意合作ARGO(Astroparticle physics Researchat Ground-based Observatory)计划，已进入大规模安装调试阶段。欲牢固占领Multi-GeV-TeV能区和满足对高可变、大峰流、短时标河外γ源的观测所需的高海拔巨型大气契仑可夫光成像望远镜计划5@YorG，也正在酝酿之中。 相似文献
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Cao Zhen Chen Ming-jun Chen Song-zhan Hu Hong-bo Liu Cheng Liu Ye Ma Ling-ling Ma Xin-hua Sheng Xiang-dong Wu Han-rong Xiao Gang Yao Zhi-guo Yin Li-qiao Zha Min Zhang Shou-shan 《Chinese Astronomy and Astrophysics》2019,43(4):457-478
Since the century discovery of cosmic ray, the origin of cosmic ray is always a mystery. The study on the origin of high-energy cosmic ray is in an interdiscipline between the very high-energy (VHE) gamma-ray astronomy and the cosmic ray physics. The Large High Altitude Air Shower Observatory (LHAASO) is a unique and new generation cosmic-ray station with the advantages of high altitude, all-weather, and large-scale. It takes the function of hybrid technology to detect cosmic rays and to upgrade greatly the resolving power between gamma rays and cosmic rays. The LHAASO is expected to make the full-sky survey to find new gamma-ray sources, to obtain the highest sensitivity of gamma-ray detection at the high energy band of > 30 TeV, and to make the very high precision measurement on the component energy spectra of cosmic rays in a broad energy range of 5 orders of magnitude, in order to provide the evidence for revealing the mystery of the origin of cosmic ray. This paper describes the detector structure, performance superiority and scientific motivation of the LHAASO. 相似文献
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Blazar emission of gamma rays and cosmic ray production of gamma rays in gas-rich clusters have been proposed recently as alternative sources of the high energy extragalactic diffuse gamma ray background radiation. We show that these sources also produce very different high energy extragalactic diffuse neutrino background radiations. An extragalactic neutrino background radiation may be detected by the new generation of large neutrino telescopes under construction and may be used to trace the origin of the extragalactic gamma radiation. 相似文献
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The IceCube experiment has detected two neutrinos with energies between 1 and 10 PeV. They might have originated from Galactic or extragalactic sources of cosmic rays. In the present work we consider hadronic interactions of the diffuse very high energy cosmic rays with the interstellar matter within our Galaxy to explain the PeV neutrino events detected in IceCube. We also expect PeV gamma ray events along with the PeV neutrino events if the observed PeV neutrinos were produced within our Galaxy in hadronic interactions. PeV gamma rays are unlikely to reach us from sources outside our Galaxy due to pair production with cosmic background radiation fields. We suggest that in future with simultaneous detections of PeV gamma rays and neutrinos it would be possible to distinguish between Galactic and extragalactic origins of very high energy neutrinos. 相似文献
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The role of nearby galactic sources, the supernova remnants, in formation of observed energy spectrum and large-scale anisotropy of high-energy cosmic rays is studied. The list of these sources is made up based on radio, X-ray and gamma-ray catalogues. The distant sources are treated statistically as ensemble of sources with random positions and ages. The source spectra are defined based on the modern theory of cosmic ray acceleration in supernova remnants while the propagation of cosmic rays in the interstellar medium is described in the frameworks of galactic diffusion model. Calculations of dipole component of anisotropy are made to reproduce the experimental procedure of “two-dimensional” anisotropy measurements. The energy dependence of particle escape time in the process of acceleration in supernova remnants and the arm structure of sources defining the significant features of anisotropy are also taken into account. The essential new trait of the model is a decreasing number of core collapse SNRs being able to accelerate cosmic rays up to the given energy, that leads to steeper total cosmic ray source spectrum in comparison with the individual source spectrum. We explained simultaneously the new cosmic ray data on the fine structure of all particle spectrum around the knee and the amplitude and direction of the dipole component of anisotropy in the wide energy range 1 TeV–1 EeV. Suggested assumptions do not look exotic, and they confirm the modern understanding of cosmic ray origin. 相似文献
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Identifying the accelerators that produce the Galactic and extragalactic cosmic rays has been a priority mission of several generations of high energy gamma ray and neutrino telescopes; success has been elusive so far. Detecting the gamma-ray and neutrino fluxes associated with cosmic rays reaches a new watershed with the completion of IceCube, the first neutrino detector with sensitivity to the anticipated fluxes, and the construction of CTA, a ground-based gamma ray detector that will map and study candidate sources with unprecedented precision. In this paper, we revisit the prospects for revealing the sources of the cosmic rays by a multiwavelength approach; after reviewing the methods, we discuss supernova remnants, gamma ray bursts, active galaxies and GZK neutrinos in some detail. 相似文献
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Gamma ray burst (GRB) fireballs provide one of very few astrophysical environments where one can contemplate the acceleration of cosmic rays to energies that exceed 1020 eV. The assumption that GRBs are the sources of the observed cosmic rays generates a calculable flux of neutrinos produced when the protons interact with fireball photons. With data taken during construction IceCube has already reached a sensitivity to observe neutrinos produced in temporal coincidence with individual GRBs provided that they are the sources of the observed extra-galactic cosmic rays. We here point out that the GRB origin of cosmic rays is also challenged by the IceCube upper limit on a possible diffuse flux of cosmic neutrinos which should not be exceeded by the flux produced by all GRB over Hubble time. Our alternative approach has the advantage of directly relating the diffuse flux produced by all GRBs to measurements of the cosmic ray flux. It also generates both the neutrino flux produced by the sources and the associated cosmogenic neutrino flux in a synergetic way. 相似文献
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With the help of empirical data concerning the latitudinal distribution of galactic gamma rays the contribution of inverse Compton scattered gamma rays is calculated using various models concerning the distribution of high energy cosmic ray electrons perpendicular to the galactic plane. It is shown that gamma ray astronomy from regions with vanishing stellar and interstellar matter densities at energies greater than 100 MeV provides instructive information on the cosmic ray electron density. We find evidence for the existence of a broad galactic electron disk with a total thickness of at least 6.4 kpc. The uncertainties of the cosmic ray electron spectrum measurements above 100 GeV imply an additional uncertainty in the inverse Compton source function of at least a factor 6. 相似文献