A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays
The dip is a feature in the diffuse spectrum of ultra-high energy (UHE) protons caused by electron-positron pair production on the cosmic microwave background (CMB) radiation. For a power-law generation spectrum $E^{-2.7}$, the calculated position and shape of the dip is confirmed with high accuracy...
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ftopenaccessrep:oai:zenodo.org:135801 2023-10-29T02:40:46+01:00 A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays Veniamin Berezinsky S. Grigorieva Bohdan Hnatyk A. Gazizov Pasquale Blasi Roberto Aloisio 2007-02-01 https://www.openaccessrepository.it/record/135801 https://doi.org/10.1016/j.astropartphys.2006.09.004 eng eng url:https://www.openaccessrepository.it/communities/itmirror https://www.openaccessrepository.it/record/135801 doi:10.1016/j.astropartphys.2006.09.004 info:eu-repo/semantics/openAccess NEANIAS Space Research Community Astronomy and Astrophysics info:eu-repo/semantics/article publication-article 2007 ftopenaccessrep https://doi.org/10.1016/j.astropartphys.2006.09.004 2023-10-03T22:18:23Z The dip is a feature in the diffuse spectrum of ultra-high energy (UHE) protons caused by electron-positron pair production on the cosmic microwave background (CMB) radiation. For a power-law generation spectrum $E^{-2.7}$, the calculated position and shape of the dip is confirmed with high accuracy by the spectra observed by the Akeno-AGASA, HiRes, Yakutsk and Fly's Eye detectors. When the particle energies, measured in these detectors, are calibrated by the dip, their fluxes agree with a remarkable accuracy. The predicted shape of the dip is quite robust. The dip is only modified strongly when the fraction of nuclei heavier than protons is high at injection, which imposes some restrictions on the mechanisms of acceleration operating in UHECR sources. The existence of the dip, confirmed by observations, implies that the transition from galactic to extragalactic cosmic rays occurs at $E \lsim 1\times 10^{18}$ eV. We show that at energies lower than a characteristic value $E_{\rm cr}\approx 1\times 10^{18}$ eV, the spectrum of extragalactic cosmic rays flattens in all cases of interest, and it provides a natural transition to a steeper galactic cosmic ray spectrum. This transition occurs at some energy below $E_{\rm cr}$, corresponding to the position of the so-called second knee. We discuss extensively the constraints on this model imposed by current knowledge of acceleration processes and sources of UHECR and compare it with the traditional model of transition at the ankle. Article in Journal/Newspaper Yakutsk Istituto Nazionale di Fisica Nucleare (INFN): Open Access Repository Astroparticle Physics 27 1 76 91 |
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Istituto Nazionale di Fisica Nucleare (INFN): Open Access Repository |
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language |
English |
topic |
NEANIAS Space Research Community Astronomy and Astrophysics |
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NEANIAS Space Research Community Astronomy and Astrophysics Veniamin Berezinsky S. Grigorieva Bohdan Hnatyk A. Gazizov Pasquale Blasi Roberto Aloisio A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays |
topic_facet |
NEANIAS Space Research Community Astronomy and Astrophysics |
description |
The dip is a feature in the diffuse spectrum of ultra-high energy (UHE) protons caused by electron-positron pair production on the cosmic microwave background (CMB) radiation. For a power-law generation spectrum $E^{-2.7}$, the calculated position and shape of the dip is confirmed with high accuracy by the spectra observed by the Akeno-AGASA, HiRes, Yakutsk and Fly's Eye detectors. When the particle energies, measured in these detectors, are calibrated by the dip, their fluxes agree with a remarkable accuracy. The predicted shape of the dip is quite robust. The dip is only modified strongly when the fraction of nuclei heavier than protons is high at injection, which imposes some restrictions on the mechanisms of acceleration operating in UHECR sources. The existence of the dip, confirmed by observations, implies that the transition from galactic to extragalactic cosmic rays occurs at $E \lsim 1\times 10^{18}$ eV. We show that at energies lower than a characteristic value $E_{\rm cr}\approx 1\times 10^{18}$ eV, the spectrum of extragalactic cosmic rays flattens in all cases of interest, and it provides a natural transition to a steeper galactic cosmic ray spectrum. This transition occurs at some energy below $E_{\rm cr}$, corresponding to the position of the so-called second knee. We discuss extensively the constraints on this model imposed by current knowledge of acceleration processes and sources of UHECR and compare it with the traditional model of transition at the ankle. |
format |
Article in Journal/Newspaper |
author |
Veniamin Berezinsky S. Grigorieva Bohdan Hnatyk A. Gazizov Pasquale Blasi Roberto Aloisio |
author_facet |
Veniamin Berezinsky S. Grigorieva Bohdan Hnatyk A. Gazizov Pasquale Blasi Roberto Aloisio |
author_sort |
Veniamin Berezinsky |
title |
A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays |
title_short |
A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays |
title_full |
A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays |
title_fullStr |
A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays |
title_full_unstemmed |
A dip in the UHECR spectrum and the transition from galactic to extragalactic cosmic rays |
title_sort |
dip in the uhecr spectrum and the transition from galactic to extragalactic cosmic rays |
publishDate |
2007 |
url |
https://www.openaccessrepository.it/record/135801 https://doi.org/10.1016/j.astropartphys.2006.09.004 |
genre |
Yakutsk |
genre_facet |
Yakutsk |
op_relation |
url:https://www.openaccessrepository.it/communities/itmirror https://www.openaccessrepository.it/record/135801 doi:10.1016/j.astropartphys.2006.09.004 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1016/j.astropartphys.2006.09.004 |
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Astroparticle Physics |
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27 |
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1 |
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76 |
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91 |
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1781069523526352896 |