Traditional image of the CR energy spectrum ( knee ) ( ankle )

Sharpness and fine structure of the spectrum in the knee region 2001, Ch 2001, Ne 2010, E0

not observed in 2006 me, Baksan me, SYB zm me, QGS mh mhe

GAMMA

KASCADE - Grande

Ice-Top single power law

Fine structure of the CR energy spectrum in the tens PeV region beyond the knee includes: * flattening of the spectrum above 20 PeV ; * possible ‘bump’ at 50 – 80 PeV; * steepening above 100 PeV.

Anatomy of the knee The fine structure can be due to the non-uniformity of the space-time distribution of CR sources with the dominant contribution of nearby and recent sources ( SNR, pulsars ). In the Single Source Model of the knee the total intensity consists of the contributions from the dominant single source and background of multiple sources. Here we estimate the contribution of ‘plural’ sources - not very old and distant, but not as strong as the dominant single source. We analysed the contribution of the second strong source and the ratio S2/S1.

Simulated energy spectra of cosmic rays for non-uniform space-time distribution of SNR What are S2/S1 here ?

Distribution of S2/S1 ratio P(>0.2)=0.08

Estimates of the contribution from the real nearby and recent sources

List of 24 nearby and recent sources: R<1.5kpc,T<120kyear ( Sveshnikova L.G. et al., 2011 )

CR energy spectra from several nearby and recent SNR

We conclude that the contribution to the knee of a few ‘plural’ sources does not exceed ~10%

Energy spectrum and mass composition of cosmic rays from the single source and Vela pulsar (Fe)

Fine structure at sub-TeV energies There is a concavity of the energy spectrum of all major CR components at hundreds GeV ( ‘ankle’ at ~200 GeV/nucleon ). Experiments: ATIC, CREAM, PAMELA

P & He

O, Mg & Fe

Concavity quantified by the ‘sagitta’

Sagittas in simulations and in the experiment

Observed curvature can be hardly explained by the random geometric configuration of cosmic ray sources

Search and the study of the fine structure of the spectrum can be an additional source of information on the nature and origin of CR in the studied energy region

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