Chemical composition and maximum energy of galactic cosmic rays
2010
8 pages
Published in:
- Astrophys.J. 716 (2010) 1076-1083
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Abstract: (IOP)
A model of the cosmic-ray energy spectrum is proposed that assumes various acceleration limits at multiple sources. The model describes the broken power-law energy spectrum of cosmic rays by superposition of multiple sources, a diffusive shock acc eleration mechanism plays an essential role. The maximum energy of galactic cosmic rays is discussed based on a comparison of experimental data with calculations done using the proposed model. The model can describe the energy spectrum at very high energi es of up to several times 10(18) eV, but the observed highest-energy cosmic rays deviate from the model predictions, indicating a different origin, such as an extragalactic source. This model describes the steepening of the power index at the so-called kn ee. However, it was found that additional assumptions are needed to explain the sharpness of the knee. Two possible explanations for the structure of the knee are discussed in terms of nearby source(s) and the hard energy spectrum suggested by nonlinear e ffects of cosmic-ray acceleration mechanisms.- cosmic radiation: energy spectrum
- cosmic radiation: acceleration
- effect: nonlinear
- galaxy
- elements: cosmic radiation
- acceleration: shock waves
- cosmic radiation: particle source
- power spectrum
- numerical calculations
- interpretation of experiments
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