At what particle energy do extragalactic cosmic rays start to predominate?

Wibig, T.; Wolfendale, A. W.

doi:10.1088/0954-3899/31/3/005

Cited by 72 publications

(84 citation statements)

References 17 publications

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“…In the majority of the ankle models, e.g. [56,57,86,23], the large fraction of the observed cosmic rays has a Galactic origin at E J 10 EeV. To facilitate the acceleration problem one should assume a heavy-nuclei composition of the new component.…”

Section: Ankle Modelmentioning

confidence: 99%

Transition from galactic to extragalactic cosmic rays

Aloisio

Berezinsky

Gazizov

2012

Astroparticle Physics

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a b s t r a c tThe study of the transition between galactic and extragalactic cosmic rays can shed more light on the end of the galactic cosmic rays spectrum and the beginning of the extragalactic one. Three models of transition are discussed: ankle, dip and mixed composition models. All these models describe the transition as an intersection of a steep galactic component with a flat extragalactic one. Severe bounds on these models are provided by the Standard Model of galactic cosmic rays according to which the maximum acceleration energy for Iron nuclei is of the order of E max Fe % 1 Â 10 17 eV. In the ankle model the transition is assumed at the ankle, a flat feature in the all particle spectrum which observationally starts at energy E a $ ð3 À 4Þ Â 10 18 eV. This model needs a new high energy galactic component with maximum energy about two orders of magnitude above that of the Standard Model. The origin of such component is discussed. As observations are concerned there are two signatures of the transition: change of energy spectra and mass composition. In all models a heavy galactic component is changed at the transition to a lighter or proton component. As a result the ankle model predicts a galactic Iron component at E < 5 Â 10 18 eV, while both HiRes and Auger data show that at ð2 À 5Þ Â 10 18 eV primaries are protons, or at least light nuclei. In the dip model the transition occurs at the second knee observed at energy ð4 À 7Þ Â 10 17 eV and is characterized by a sharp change of mass composition from galactic Iron to extragalactic protons. The ankle in this model appears automatically as a part of the e þ e À pair-production dip. The mixed composition model describes transition at E $ 3 Â 10 18 eV with mass composition changing from the galactic Iron to extragalactic mixed composition of different nuclei. In most mixed composition models the spectrum is proton-dominated and it better fits HiRes than Auger data. The latter show a steadily heavier mass composition with increasing energy, and we discuss the models which explain it.

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Section: Ankle Modelmentioning

confidence: 99%

Transition from galactic to extragalactic cosmic rays

Aloisio

Berezinsky

Gazizov

2012

Astroparticle Physics

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“…We also considered later transition models such as the classic ankle model considered for instance by Wibig & Wolfendale (2005). For that purpose a β = 2.0 spectral index is assumed for all evolution models.…”

Section: Classic Ankle and Late-transition Modelsmentioning

confidence: 99%

Constraints on the origin of ultra-high-energy cosmic rays from cosmogenic neutrinos and photons

Decerprit¹,

Allard

2011

A&A

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We study the production of cosmogenic neutrinos and photons during the extragalactic propagation of ultra-high-energy cosmic rays (UHECRs). For a wide range of models in cosmological evolution of source luminosity, composition and maximum energy we calculate the expected flux of cosmogenic secondaries by normalizing our cosmic ray output to experimental spectra and comparing the diffuse flux of GeV−TeV gamma-rays to the experimental one measured by the Fermi satellite. Most of these models yield significant neutrino fluxes for current experiments like IceCube or Pierre Auger. Furthermore, we discuss the possibilities of signing the presence of UHE proton sources either within or outside the cosmic ray horizon using neutrinos or photons observations even if the cosmic ray composition becomes heavier at the highest energies. We discuss the possible constraints that could be brought on the UHECR origin from the different messengers and energy ranges.

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“…In particular, it will permit to decide among the three main models: (i) the mixed composition scenario [15], in which the composition injected by the extragalactic sources is assumed to be similar to the one of the Galactic sources and in which the transition takes place in the ankle region, (ii) the dip model [16], in which the ankle is originated by the interaction of extragalactic protons with the cosmic microwave background and the transition is given at the second knee and (iii) a two-component transition from Galactic iron nuclei to extragalactic protons, around the ankle energy [18].…”

Section: Introductionmentioning

confidence: 99%

Underground muon counters as a tool for composition analyses

Supanitsky

Etchegoyen

Medina‐Tanco

et al. 2008

Astroparticle Physics

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The transition energy from galactic to extragalactic cosmic ray sources is still uncertain, but it should be associated either with the region of the spectrum known as the second knee or with the ankle. The baseline design of the Pierre Auger Observatory was optimized for the highest energies. The surface array is fully efficient above 3 × 10 18 eV and, even if the hybrid mode can extend this range below 10 18 eV, the second knee and a considerable portion of the wide ankle structure are left outside its operating range. Therefore, in order to encompass these spectral features and gain further insight into the cosmic ray composition variation along the transition region, enhancements to the surface and fluorescence components of the baseline design are being implemented that will lower the full efficiency regime of the Observatory down to ∼ 10 17 eV. The surface enhancements consist of a graded infilled area of standard Auger water Cherenkov detectors deployed in two triangular grids of 433 m and 750 m of spacing. Each surface station inside this area will have an associated muon counter detector. The fluorescence enhancement, on the other hand, consists of three additional fluorescence telescopes with higher elevation angle (30 • − 58 • ) than the ones in operation at present. The aim of this paper is threefold. We study the effect of the segmentation of the muon counters and find an analytical expression to correct for the under counting due to muon pile-up. We also present a detailed method to reconstruct the muon lateral distribution function for the 750 m spacing array. Finally, we study the mass discrimination potential of a new parameter, the number of muons at 600 m from the shower axis, obtained by fitting the muon data with the above mentioned reconstruction method.

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At what particle energy do extragalactic cosmic rays start to predominate?

Cited by 72 publications

References 17 publications

Transition from galactic to extragalactic cosmic rays

Transition from galactic to extragalactic cosmic rays

Constraints on the origin of ultra-high-energy cosmic rays from cosmogenic neutrinos and photons

Underground muon counters as a tool for composition analyses

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