The anisotropy of galactic cosmic rays as a product of stochastic supernova explosions

We study the effect of the stochastic character of supernova explosions on the anisotropy of galactic cosmic rays below the knee. We conclude that if the bulk of cosmic rays are produced in supernova explosions the observed small and nearly energy independent amplitude of the anisotropy and its phase are to the large extent determined by the history of these explosions in the vicinity of the solar system, namely by the location and the age of the supernova remnants, within a few kpc, which give the highest contribution to the total intensity at the present epoch. Among the most important factors which result in the small magnitude and the energy independence of the anisotropy amplitude are the mixed primary mass composition, the effect of the single source and the galactic Halo. Special attention is given to the phase of the anisotropy. It is shown that the excessive cosmic ray flux from the outer Galaxy can be due to the location of the solar system at the inner edge of the Orion arm which has the enhanced density and rate of supernova explosions

How Should We Modify the High Energy Interaction Models ?

An analysis has been made of the present situation with respect to the high energy hadron-nucleus and nucleus-nucleus interaction models as applied to cosmic rays. As is already known, there are inconsistencies in the interpretation of experimental data on the primary mass composition, which appear when different EAS components are used for the analyses, even for the same experiment. In the absence of obvious experimental defects, there is a clear need for an improvement to the existing models; we argue that the most promising way is to enlist two effects which should be present in nucleus- nucleus collisions but have not been allowed for before. These are: a few percent energy transfer into the EAS electromagnetic component due to electron- positron pair production or electromagnetic radiation of the quark-gluon plasma and a small slow-down of the cascading process in its initial stages associated with the extended lifetime of excited nuclear fragments. The latter process displaces the shower maximum deeper into the atmosphere.Comment: 4 pages, 3 figures, talk presented at XII International Symposium on Very High Energy Cosmic Ray Interactions, CERN, Geneva, 15-19 July 2002, to be published in Nucl.Phys.B (Proc. Suppl.

Fine structure in the gamma-ray sky and the origin of UHECR

The EGRET results for gamma ray intensities in and near the Galactic Plane have been analysed in some detail. Attention has been concentrated on energies above 1 GeV and the individual intensities in a $4^{\circ}$ longitude bin have been determined and compared with the large scale mean found from a nine-degree polynomial fit. Comparison has been made of the observed standard deviation for the ratio of these intensities with that expected from variants of our model. The basic model adopts cosmic ray origin from supernova remnants, the particles then diffusing through the Galaxy with our usual `anomalous diffusion'. The variants involve the clustering of SN, a frequency distribution for supernova explosion energies, and 'normal', rather than 'anomalous' diffusion. It is found that for supernovae of unique energy, and our usual anomalous diffusion, clustering is necessary, particularly in the Inner Galaxy. An alternative, and preferred, situation is to adopt the model with a frequency distribution of supernova energies. The results for the Outer Galaxy are such that no clustering is required. If their explosion energies are distributed then supernovae can be the origin of UHECR.Comment: 8 pages, 5 figures and 1 table, to appear in the proceedings of the CRIS2006 symposium, Catania, Italy, May-June 200

The Anatomy of the Knee and Gamma-Families

It is shown that the fine stucture of the cosmic ray energy spectrum in the knee region, if explained by the Single Source Model (SSM), can, in principle, be clearly revealed and magnified in the size spectrum of extensive air showers (EAS) associated with gamma families. Existing experimental data on EAS at mountain level give support to this hypothesis.Comment: 4 pages, 3 figures, to appear in the Proceedings of 14th International Symposium on Very High Energy Cosmic Ray Interactions, Weihai, China, 15-22.08.06, Nucl.Phys.B (Proc.Suppl.), 200

Spectral Features and Masses in the PeV Region

An analysis is made of the masses and spectral features for cosmic rays in the PeV region, insofar as they have a bearing on the problem of the interaction of cosmic ray particles. In our Single Source Model we identified two 'peaks' seen in a summary of the world's data on primary spectra, and claimed that they are probably due to oxygen and iron nuclei from a local, recent supernova. In the present work we examine other possible mass assignments. We conclude that of the other possibilities only Helium and Oxygen (instead of O and Fe) has much chance of success; the original suggestion is still preferred, however. Concerning our location with respect to the SNR shell, the analysis suggests that we are close to it - probably just inside.Comment: 4 pages, 2 figures, talk presented at XII Inrternational Symposium on Very High Energy Cosmic Ray Interactions, CERN, Geneva, 15-19 July 2002, to be published in Nucl.Phys.B (Proc.Suppl.

The contribution of cosmic rays to global warming

A search has been made for a contribution of the changing cosmic ray intensity to the global warming observed in the last century. The cosmic ray intensity shows a strong 11 year cycle due to solar modulation and the overall rate has decreased since 1900. These changes in cosmic ray intensity are compared to those of the mean global surface temperature to attempt to quantify any link between the two. It is shown that, if such a link exists, the changing cosmic ray intensity contributes less than 8% to the increase in the mean global surface temperature observed since 1900.Comment: 12 pages, 5 figures, accepted for publication in J. of Atmospheric and Solar-Terrestrial physic

Models for the Origin of the Knee in the Cosmic-Ray Spectrum

A sudden steepening of the cosmic-ray energy spectrum (the knee) is observed at an energy of about 3 PeV (1 PeV = $10^{15}$ eV). The experimental study of the PeV cosmic rays has intensified greatly during the last 3 years. The recent results on extensive air showers allow us to conclude that: a) the knee has an astrophysical origin; b) the `sharpness' and the fine structure of the knee rule out `Galactic Modulation' as the origin of the knee; c) most likely the knee is the result of the explosion of a single, recent, nearby supernova.Comment: 10 pages, 6 figures, submitted to Advances in Space Researc