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Astron. Astrophys. 349, 259-266 (1999)

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Galactic [FORMULA]-ray bursters - an alternative source of cosmic rays at all energies

Arnon Dar 1,2 and Rainer Plaga 2

1 Department of Physics and Space Research Institute, Technion, Haifa 32000, Israel
2 Max-Planck-Institut für Physik, Föhringer Ring 6, D-80805 München, Germany

Received 10 February 1999 / Accepted 22 June 1999


We propose a new hypothesis for the origin of the major part of non-solar hadronic cosmic rays (CRs) at all energies: highly relativistic, narrowly collimated jets from the birth or collapse of neutron stars (NSs) in our Galaxy accelerate ambient disk and halo matter to CR energies and disperse it in hot spots which they form when they stop in the Galactic halo. Such events are seen as cosmological gamma-ray bursts (GRBs) in other galaxies when their beamed radiation happens to point towards Earth. This source of CRs is located in the Galactic halo. It therefore explains the absence of the Greisen-Zatsepin-Kuz'min cutoff in the spectrum of the ultra-high energy CRs. The position in energy of the "ankle" in the CR energy spectrum is shown to arise in a natural way. Moreover, an origin of lower energy CRs in the Galactic halo naturally accounts for the high degree of isotropy of CRs around 100 TeV from airshower observations, and the small galactocentric gradient of low-energy CRs derived from gamma-ray observations.

Key words: acceleration of particles – ISM: cosmic rays – Galaxy: halo – galaxies: jets – gamma rays: bursts

Send offprint requests to: plaga@mppmu.mpg.de

© European Southern Observatory (ESO) 1999

Online publication: August 25, 1999