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Title: Anomalous Galactic Cosmic Rays in the Framework of AMS-02

Abstract

The cosmic-ray (CR) energy spectra of protons and helium nuclei, which are the most abundant components of cosmic radiation, exhibit a remarkable hardening at energies above 100 GeV/nucleon. Recent data from AMS-02 confirm this feature with a higher significance. These data challenge the current models of CR acceleration in Galactic sources and propagation in the Galaxy. Here, we explain the observed break in the spectra of protons and helium nuclei in light of recent advances in CR diffusion theories in turbulent astrophysical sources as being a result of a transition between different CR diffusion regimes. We reconstruct the observed CR spectra using the fact that a transition from normal diffusion to superdiffusion changes the efficiency of particle acceleration and causes the change in the spectral index. We find that calculated proton and helium spectra match the data very well.

Authors:
 [1]; ;  [2]
  1. National Central University (NCU), ChungLi, Tao Yuan, 32054, Taiwan (China)
  2. Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)
Publication Date:
OSTI Identifier:
22663924
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ASTROPHYSICS; COMPUTERIZED SIMULATION; COSMIC ALPHA PARTICLES; COSMIC PROTONS; COSMIC RADIATION; DIFFUSION; EFFICIENCY; ENERGY SPECTRA; GALAXIES; GALAXY NUCLEI; GEV RANGE; HELIUM; SHOCK WAVES; SUPERNOVA REMNANTS; TURBULENCE; VISIBLE RADIATION

Citation Formats

Khiali, Behrouz, Haino, Sadakazu, and Feng, Jie, E-mail: behrouz.khiali@cern.ch. Anomalous Galactic Cosmic Rays in the Framework of AMS-02. United States: N. p., 2017. Web. doi:10.3847/1538-4357/835/2/229.
Khiali, Behrouz, Haino, Sadakazu, & Feng, Jie, E-mail: behrouz.khiali@cern.ch. Anomalous Galactic Cosmic Rays in the Framework of AMS-02. United States. doi:10.3847/1538-4357/835/2/229.
Khiali, Behrouz, Haino, Sadakazu, and Feng, Jie, E-mail: behrouz.khiali@cern.ch. Wed . "Anomalous Galactic Cosmic Rays in the Framework of AMS-02". United States. doi:10.3847/1538-4357/835/2/229.
@article{osti_22663924,
title = {Anomalous Galactic Cosmic Rays in the Framework of AMS-02},
author = {Khiali, Behrouz and Haino, Sadakazu and Feng, Jie, E-mail: behrouz.khiali@cern.ch},
abstractNote = {The cosmic-ray (CR) energy spectra of protons and helium nuclei, which are the most abundant components of cosmic radiation, exhibit a remarkable hardening at energies above 100 GeV/nucleon. Recent data from AMS-02 confirm this feature with a higher significance. These data challenge the current models of CR acceleration in Galactic sources and propagation in the Galaxy. Here, we explain the observed break in the spectra of protons and helium nuclei in light of recent advances in CR diffusion theories in turbulent astrophysical sources as being a result of a transition between different CR diffusion regimes. We reconstruct the observed CR spectra using the fact that a transition from normal diffusion to superdiffusion changes the efficiency of particle acceleration and causes the change in the spectral index. We find that calculated proton and helium spectra match the data very well.},
doi = {10.3847/1538-4357/835/2/229},
journal = {Astrophysical Journal},
number = 2,
volume = 835,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
  • Recently, AMS-02 reported their results of cosmic ray (CR) observations. In addition to the AMS-02 data, we add HESS data to estimate the spectra of CR electrons and the diffuse gamma rays above TeV. In the conventional diffusion model, a global analysis is performed on the spectral features of CR electrons and the diffuse gamma rays by the GALRPOP package. The results show that the spectrum structure of the primary component of CR electrons cannot be fully reproduced by a simple power law and that the relevant break is around 100 GeV. At the 99% confidence level (C.L.) the injectionmore » indices above the break decrease from 2.54 to 2.35, but the ones below the break are only in the range of 2.746–2.751. The spectrum of CR electrons does not need to add TeV cutoff to also match the features of the HESS data. Based on the difference between the fluxes of CR electrons and their primary components, the predicted excess of CR positrons is consistent with the interpretation that these positrons originate from a pulsar or dark matter. In the analysis of the Galactic diffuse gamma rays with the indirect constraint of AMS-02 and HESS data, it is found that the fluxes of Galactic diffuse gamma rays are consistent with the GeV data of the Fermi-Large Area Telescope (LAT) in the high-latitude regions. The results indicate that inverse Compton scattering is the dominant component in the range of hundreds of GeV to tens of TeV, respectively from the high-latitude regions to the low ones, and in all of the regions of the Galaxy the flux of diffuse gamma rays is less than that of CR electrons at the energy scale of 20 TeV.« less
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