Nearby sources in the transition region between Galactic and Extragalactic cosmic rays

Abstract

In this paper, a probable interpretation of a remarkable fine structure of all particle spectra between the knee and the ankle, as well as a high content of heavy nuclei around 10 17 eV measured recently in Tunka-133 and KASCADE Grande experiments, is presented in the model where production of cosmic rays in Type Ia SNRs provides observed cosmic rays (CR) flux around the knee. Subtracting the contribution of these sources from all particle spectrum we obtained the residual flux of CR in the transition region between Galactic and Extragalactic CR in the range 10 17 5 10 18 eV. The obtained spectrum also has a pronounced knee at energy (23)10 17 eV and slopes  1 ~ 1.80.3 below it and  2 ~3.4 above it. We analyzed the possible contribution from known Galactic sources and found that formally the best candidate to contribute significantly to the transition region is Cas A. This source posses a number of unusual properties and considered as Type IIb SNR. However we showed that the hypothesis of extragalactic origin of CR starting from 10 17 eV seems more realistic.

Ultra-high energy cosmic rays: 40 years retrospective of continuous observations at the Yakutsk array: Part 1. Cosmic ray spectrum in the energy range 1015–1018 eV and its interpretation

“…Ultimately, the chemical composition of galactic cosmic rays at 1 TeV becomes different from "normal" composition (17% of H, 46% of He, 8% of CNO, 16% of Fe). Thus calculations of the spectra obtained in [15] practically coincide with the experimental data, indicating the existence of a second knee in the energy range 10 17 -10 18 eV, i.e. at ∼ 2 · 10 17 eV.…”

“…at ∼ 2 · 10 17 eV. Thus, a second knee, as predicted in obtained in [14] and shown by calculations [15], formed by a sharp steepening of the spectrum of galactic iron nuclei in the energy range (2-8) · 10 16 eV at 4 · 26 PeV and growth of contribution of metagalactic protons from 2· 10 16 eV, which leads to the formation of the second knee.…”

“…7). The purpose of these calculations was the interpretation of the 04001-p.4 [14,15]. Galactic cosmic rays are presented separately: dark green line (total), red line (H+He), blue line (Z>6), green line (Z>14), orange line (Z>20).…”

“…Data about the CR spectrum obtained recently at the compact array can serve as proof of this. Figure 7 shows the partial spectra for individual nuclei and total spectra of all particles separately for the galactic component (obtained in [15], using the above described assumptions about the magnetic fields, the source model and varying the chemical composition of the particles to the galactic component). It is believed that cosmic rays are produced and accelerated in SNRs to energies E max by the law N (> E max ) ∼ E −0.17 max [14] and the upper limit of the acceleration of galactic cosmic rays E = 26 · (4 ± 1) PeV.…”

The Knees-Ankles-Toe in Cosmic Rays and the Periodic Table of Elementary Particles

“…The fine structure of the cosmic ray spectrum measured in Tunka-133 [6] and KASCADE Grande [7] [8] experiments shows that the spectrum in the energy range of 10 16 to 10 18 eV cannot be fitted with single power index. The power index decreases around 2 × 10 16 eV for spectrum hardening and increases around 3 × 10 17 eV for spectrum steepening.…”