Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants | |
Zhang, Yiran1,2; Liu, Siming1,2![]() ![]() | |
刊名 | ASTROPHYSICAL JOURNAL LETTERS
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2017-07-20 | |
卷号 | 844期号:1页码:5 |
关键词 | acceleration of particles cosmic rays ISM: supernova remnants shock waves |
ISSN号 | 2041-8205 |
DOI | 10.3847/2041-8213/aa7de1 |
英文摘要 | Recent precise measurements of cosmic-ray (CR) spectra show that the energy distribution of protons is softer than those of heavier nuclei, and there are spectral hardenings for all nuclear compositions above similar to 200 GV. Models proposed for these anomalies generally assume steady-state solutions of the particle acceleration process. We show that if the diffusion coefficient has a weak dependence on the particle rigidity near shock fronts of supernova remnants (SNRs), time-dependent solutions of the linear diffusive shock acceleration at two stages of SNR evolution can naturally account for these anomalies. The high-energy component of CRs is dominated by acceleration in the free expansion and adiabatic phases with enriched heavy elements and a high shock speed. The low-energy component may be attributed to acceleration by slow shocks propagating in dense molecular clouds with low metallicity in the radiative phase. Instead of a single power-law distribution, the spectra of time-dependent solutions soften gradually with the increase of energy, which may be responsible for the "knee" of CRs. |
WOS关键词 | DIFFUSIVE SHOCK ACCELERATION ; HELIUM SPECTRA ; RX J1713.7-3946 ; PROTON ; ORIGIN ; FLIGHT |
WOS研究方向 | Astronomy & Astrophysics |
语种 | 英语 |
出版者 | IOP PUBLISHING LTD |
WOS记录号 | WOS:000405607900003 |
内容类型 | 期刊论文 |
源URL | [http://libir.pmo.ac.cn/handle/332002/22877] ![]() |
专题 | 中国科学院紫金山天文台 |
通讯作者 | Liu, Siming |
作者单位 | 1.Chinese Acad Sci, Purple Mt Observ, Key Lab Dark Matter & Space Astron, Nanjing 210008, Jiangsu, Peoples R China 2.Univ Sci & Technol China, Sch Astron & Space Sci, Hefei 230026, Anhui, Peoples R China |
推荐引用方式 GB/T 7714 | Zhang, Yiran,Liu, Siming,Yuan, Qiang. Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants[J]. ASTROPHYSICAL JOURNAL LETTERS,2017,844(1):5. |
APA | Zhang, Yiran,Liu, Siming,&Yuan, Qiang.(2017).Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants.ASTROPHYSICAL JOURNAL LETTERS,844(1),5. |
MLA | Zhang, Yiran,et al."Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants".ASTROPHYSICAL JOURNAL LETTERS 844.1(2017):5. |
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