The radial gradient of cosmic ray intensity in the Galaxy

Abstract

The dependence of the cosmic ray intensity on Galactocentric distance is known to be much less rapid than that to be thought-to-be sources: supernova remnants. This is an old problem ('the radial gradient problem') which has led to a number of possible 'scenarios'. Here, we use recent data on the supernova's radial distribution and correlate it with the measured HII electron temperature ({\em T}). We examined two models of cosmic ray injection and acceleration and in both of them the injection efficiency increases with increasing ambient temperature {\em T}. The increase is expected to vary as a high power of {\em T} in view of the strong temperature dependence of the tail of the Maxwell-Boltzmann distribution of particle energies. Writing the efficiency as proportional to $T^n$ we find $n\approx 8.4$. There is thus, yet another possible explanation of the radial gradient problem.

12 pages, 5 figures, accepted by 'Advances in Space Research'

References in corpus (3)

• The Electron Temperature Gradient in the Galactic Disk
• Constraints on the distribution of supernova remnants with Galactocentric radius
• NanoSIMS, TEM, and XANES studies of a Unique Presolar Supernova Graphite Grain

Cited by in corpus (6)

• Bayesian analysis of cosmic-ray propagation: evidence against homogeneous diffusion
• On the radial distribution of Galactic cosmic rays
• Cosmic-Ray Lithium Production at the Nova Eruption Followed by a Type Ia Supernova
• Selected Topics in Cosmic Ray Physics
• The Local Bubble in the interstellar medium and the origin of the low energy cosmic rays
• Effects of self-generated turbulence on Galactic Cosmic Ray propagation and associated diffuse gamma-ray emission