Turbulent diffusion and drift in galactic magnetic fields and the explanation of the knee in the cosmic ray spectrum

Candia, Julián; Roulet, Esteban; Epele, L.N.

doi:10.1088/1126-6708/2002/12/033

Cited by 42 publications

(87 citation statements)

References 26 publications

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“…The physics of this feature is still unknown, it might be due to the end of the efficiency of supernova remnant shock waves as accelerators or a change in the diffusion regime in our Galaxy [11,12].…”

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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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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“…[13,17], and hereafter referred as the diffusion/drift model. This analysis will be done for the whole range of energies in which drift effects are relevant (E > E knee ) and where CRs are dominated by the galactic component (E < E ankle ≃ 5 × 10 18 eV).…”

Section: Introductionmentioning

confidence: 99%

Cosmic ray spectrum and anisotropies from the knee to the second knee

Candia

Mollerach

Roulet

2003

J. Cosmol. Astropart. Phys.

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We consider the scenario in which the knee in the cosmic ray spectrum is due to a change in the escape mechanism of cosmic rays from the Galaxy from one dominated by transverse diffusion to one dominated by drifts. We show that this scenario explains not only the changes in spectral slope at the knee and at the second knee, but can also account for the main characteristics of the observed energy dependent anisotropy amplitude and phase of first harmonic in the energy range between 10 15 and 10 18 eV. This provides a useful handle to distinguish this diffusion/drift model from other scenarios proposed to explain the knee in the spectrum.

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“…The field is normalized to have an average strength of 4 G at the Solar System position. Its strength is diminishing with height above the Galactic Plane and the distance from the Galactic Centre following the regular field model of [21,22].…”

Section: Angular Deflections In the Galactic Magnetic Fieldmentioning

confidence: 93%

“…The field was chosen to be symmetric with respect to the Galactic Plane. The halo around the disk is filled with the field similar to that in the disk but diminishing slowly with the distance from the Galactic Plane on a scale of few kpc ( [21,22]), but it can be also the dipole field ( [23]) as suggested by the dynamo mechanism. For the random component we have used the Kolmogorov turbulent field with a spectrum of turbulences ranging from 1 to 100 pc length scales.…”

Section: Angular Deflections In the Galactic Magnetic Fieldmentioning

confidence: 99%

Heavy Cosmic Ray Nuclei from Extragalactic Sources above ‘The Ankle '

Wibig¹,

Wolfendale²

2009

TOAAJ

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A recent observation by the Auger Observatory group presents evidence for cosmic rays above 5.6 10 19 eV -(56 EeV) being 'predominantly protons' coming from Active Galactic Nuclei. If, as would be expected, the particles above the ankle at about 2 EeV are almost all of Extragalactic origin then it follows that the characteristics of the nuclear interactions of such particles would need to be very different from conventional expectation -a result that follows from the measured positions of 'shower maximum' at somewhat lower energies where mass measurements using conventional nuclear interaction models indicate (ln A)≃ 2.5. Such a claim is rather dramatic.In our own analysis we study to what extent the Auger results could, indeed, give such a mean value for (ln A)rather than a much smaller one. We conclude that they can, and the need for a dramatic change in the nuclear physics disappears.PACS numbers: 96.50.sb, 96.50.sd, 98.70.Sa.

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Turbulent diffusion and drift in galactic magnetic fields and the explanation of the knee in the cosmic ray spectrum

Cited by 42 publications

References 26 publications

Underground muon counters as a tool for composition analyses

Underground muon counters as a tool for composition analyses

Cosmic ray spectrum and anisotropies from the knee to the second knee

Heavy Cosmic Ray Nuclei from Extragalactic Sources above ‘The Ankle '

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