Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants

	Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants
	Zhang, Yiran; Liu, Siming; Yuan, Qiang
刊名	ASTROPHYSICAL JOURNAL LETTERS
	2017
卷号	844 期号:1 页码:L3-
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.
语种	英语
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/17476]
专题	中国科学院紫金山天文台
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):L3-.
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),L3-.
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):L3-.