Energy spectra of the main groups of galactic cosmic rays in the model of three classes of sources

We suggest a model to consistently describe the available experimental data on the elemental cosmic-ray energy spectra obtained in direct measurements and to make a smooth transition to the spectrum of all particles measured with extensive air showers. The model suggests the existence of three classes of cosmic-ray sources—shocks from supernova explosions that produce power-law rigidity spectra with different maximum rigidities and different spectral indices. The shocks from high-mass supernovae exploding in OB associations are assumed to be the most powerful class of sources. This class of sources accelerates cosmic rays to a maximum rigidity of 4 × 10¹⁵ V. The shocks from nonassociated supernovae exploding into a random interstellar medium are assumed to be the next class (in order of decreasing power). This class of sources accelerates cosmic rays to a maximum rigidity of 5 × 10¹³ V. The third, weakest class of sources is assumed to accelerate cosmic rays to a maximum rigidity of 2 × 10¹¹ V. Nova explosions could be possible physical objects in this class.