Propagation of cosmic rays in the galaxy

Journal Article · Thu Jun 01 04:00:00 EDT 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156160· OSTI ID:6735563

Ormes, J; Freier, P

The details of the leaky-box model for cosmic-ray propagation are presented. The nuclear composition data indicate that the propagation is rigidity dependent. The escape length can be represented by lambda/sub e/proportionalR/sup -0.4plus-or-minus0.1/ above 7.6 GV and lambda/sub e/=5.5 g cm/sup -2/ below 7.6 GV. From this it follows that the injection spectra of all species must be power laws in total energy or rigidity with dN/dEproportionalE/sup -gamma/0 with ..gamma../sub 0/=2.3 +- 0.1. The electron data can also be fitted by using a similar injection spectrum, and both the electron and /sup 10/Be data are compatible with a lifetime of 1-2 x 10/sup 7/ years. The mean density in the storage volume must be 0.15--0.3 atoms cm/sup -3/. These data support the assumption that electrons and nuclei have a similar origin within the Galaxy, presumably associated with supernova remnants. Commparison of the lifetime data and the leakage length with radio synchrotron and ..gamma..-ray data suggests that the bulk of cosmic rays observed at Earth originate within a 0.5--1 kpc radius around us. Consequences of the model at energies above those currently observed and for the rarer components of the radiation are examined. The model predicts that the spectra of Z>30 nuclei will most closely reflect the source spectrum. If the escape length continues to decrease above 100 GeV per nucleon as R/sup -0.4/, the asymptotic spectra of primary nuclei will all approach E/sup -2.7/, the secondary nuclei E/sup -3.1/, the electron spectrum E/sup -3.3/, and the positron spectrum E/sup() -3.5en-dash3.7/. If the escape length becomes energy-independent all nuclear spectra will flatten to E/sup -2.3/ again, whereas the electron spectrum would be unchanged (E/sup -3.3/).

• Research Organization: School of Physics and Astronomy, University of Minnesota
• OSTI ID: 6735563
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 222:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BREMSSTRAHLUNG
COSMIC ELECTRONS
COSMIC NUCLEI
COSMIC RADIATION
COSMIC RADIO SOURCES
COSMIC RAY PROPAGATION
COSMIC RAY SOURCES
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY SPECTRA
FERMIONS
GALAXIES
GAMMA RADIATION
IONIZING RADIATIONS
LEPTONS
MILKY WAY
NUCLEI
RADIATIONS
SPECTRA
SUPERNOVA REMNANTS
SYNCHROTRON RADIATION