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Title: Nonuniversal spectra of ultrahigh energy cosmic ray primaries and secondaries in a structured universe

Abstract

Analytical calculations of extragalactic cosmic ray spectra above {approx}10{sup 17} eV are often performed assuming continuous source distributions, giving rise to spectra that depend little on the propagation mode, be it rectilinear or diffusive. We perform trajectory simulations for proton primaries in the probably more realistic case of discrete sources with a density of {approx}10{sup -5} Mpc{sup -3}. We find two considerable nonuniversal effects that depend on source distributions and magnetic fields: First, the primary extragalactic cosmic ray flux can become strongly suppressed below a few 10{sup 18} eV due to partial confinement in magnetic fields surrounding sources. Second, the secondary photon to primary cosmic ray flux ratio between {approx_equal}3x10{sup 18} eV and {approx_equal}10{sup 20} eV decreases with decreasing source density and increasing magnetization. As a consequence, in acceleration scenarios for the origin of highest energy cosmic rays the fraction of secondary photons may be difficult to detect even for experiments such as Pierre Auger. The cosmogenic neutrino flux does not significantly depend on source density and magnetization.

Authors:
 [1]
  1. APC - AstroParticules et Cosmologie, 10, rue Alice Domon et Leonie Duquet, 75205 Paris Cedex 13 (France) and Institut d'Astrophysique de Paris, UMR 7095 CNRS - Universite Pierre and Marie Curie, 98 bis Boulevard Arago, F-75014 Paris (France)
Publication Date:
OSTI Identifier:
20933285
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 10; Other Information: DOI: 10.1103/PhysRevD.75.103001; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCELERATION; CONFINEMENT; COSMIC RAY FLUX; EEV RANGE; MAGNETIC FIELDS; MAGNETIZATION; NEUTRINOS; PHOTONS; PRIMARY COSMIC RADIATION; PROTONS; SIMULATION; TRAJECTORIES; UNIVERSE

Citation Formats

Sigl, Guenter. Nonuniversal spectra of ultrahigh energy cosmic ray primaries and secondaries in a structured universe. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.103001.
Sigl, Guenter. Nonuniversal spectra of ultrahigh energy cosmic ray primaries and secondaries in a structured universe. United States. doi:10.1103/PHYSREVD.75.103001.
Sigl, Guenter. Tue . "Nonuniversal spectra of ultrahigh energy cosmic ray primaries and secondaries in a structured universe". United States. doi:10.1103/PHYSREVD.75.103001.
@article{osti_20933285,
title = {Nonuniversal spectra of ultrahigh energy cosmic ray primaries and secondaries in a structured universe},
author = {Sigl, Guenter},
abstractNote = {Analytical calculations of extragalactic cosmic ray spectra above {approx}10{sup 17} eV are often performed assuming continuous source distributions, giving rise to spectra that depend little on the propagation mode, be it rectilinear or diffusive. We perform trajectory simulations for proton primaries in the probably more realistic case of discrete sources with a density of {approx}10{sup -5} Mpc{sup -3}. We find two considerable nonuniversal effects that depend on source distributions and magnetic fields: First, the primary extragalactic cosmic ray flux can become strongly suppressed below a few 10{sup 18} eV due to partial confinement in magnetic fields surrounding sources. Second, the secondary photon to primary cosmic ray flux ratio between {approx_equal}3x10{sup 18} eV and {approx_equal}10{sup 20} eV decreases with decreasing source density and increasing magnetization. As a consequence, in acceleration scenarios for the origin of highest energy cosmic rays the fraction of secondary photons may be difficult to detect even for experiments such as Pierre Auger. The cosmogenic neutrino flux does not significantly depend on source density and magnetization.},
doi = {10.1103/PHYSREVD.75.103001},
journal = {Physical Review. D, Particles Fields},
number = 10,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}