The anisotropy of cosmic ray arrival directions around 1018 eV

Hayashida, N.; Honda, K.; Inoue, N.; Kadota, K.; Kakimoto, F.; Kakizawa, Shigeyuki; Kamata, K.; Kawaguchi, S.; Kawasaki, Y.; Kawasumi, N.; Kusano, Eiji; Matsubara, Y.; Mase, K.; Minagawa, T.; Murakami, Kazuaki; Nagano, M.; Nishikawa, D.; Ohoka, H.; Osone, S.; Sakaki, N.; Sasaki, Misao; Sasano, M.; Shinozaki, K.; Takeda, M.; Teshima, M.; Torii, R.; Tsushima, I.; Uchihori, Y.; Yamamoto, T.; Yoshida, Shigeru; Yoshii, H.

doi:10.1016/s0927-6505(98)00064-4

Cited by 214 publications

(201 citation statements)

References 9 publications

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“…In the energy region near 10 17 eV, an amplitude (1.52Ϯ0.44)% was found at RAϭ212°Ϯ17°with a chance probability of 0.3% (Lloyd-Evans and . The Yakutsk group claimed a significant anisotropy of an amplitude (1.35Ϯ0.36)% with a chance probability of 0.09% in the energy region 3ϫ10 16 -3 In AGASA data an anisotropy of amplitude 4% around 10 18 eV was found in the first harmonic analysis (Hayashida et al, 1999a(Hayashida et al, , 1999b with accumulated data of more than 2ϫ10 5 events above 10 17 eV. A significance map of event excess between 8ϫ10 17 and 2 ϫ10 18 eV is shown in Fig.…”

Section: Comparison With the Spectrum In The Lower-energy Regionmentioning

confidence: 94%

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Observations and implications of the ultrahigh-energy cosmic rays

2000

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The authors define ''ultrahigh-energy cosmic rays'' (UHECRs) as those cosmic rays with energies above 10 18 eV. It had been anticipated that there would be a cutoff in the energy spectrum of primary cosmic rays around 6ϫ10 19 eV induced by the interaction of the particles with the 2.7-K primordial photons. However, recent experimental data have established that particles exist with energies greatly exceeding this. It follows that the sources of such particles are probably nearby, on a cosmological scale. However, although the trajectories of such energetic particles through the galactic and intergalactic magnetic fields may be nearly rectilinear, no astronomical sources have as yet been identified. This is the enigma of the highest-energy cosmic rays. The paper reviews the history of research in this energy regime and critically assesses the observational results on the energy spectrum, arrival directions, and composition of the primary cosmic rays based on observations made by six experiments. The detection methods currently available are described. Special techniques have been developed as particles of 10 20 eV or higher occur at a rate of only about 1 per km 2 per century. Errors in measurement are given particular attention. The authors also review the theoretical predictions for a number of candidate sources of cosmic rays beyond the predicted cutoff. Finally, the four major projects planned to address the question of the origin of UHECRs are briefly described. CONTENTS

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Section: Comparison With the Spectrum In The Lower-energy Regionmentioning

confidence: 94%

“…Although AGASA has not observed any such short-period excess from the direction of Cyg X-3 since 1990, it should be noted that there are excess events from the directions of the galactic center and the Cygnus region between 8ϫ10 17 and 2 ϫ10 18 eV, as shown in Fig. 25 (Hayashida et al, 1999a(Hayashida et al, , 1999b.…”

Section: Neutron Primariesmentioning

confidence: 96%

Observations and implications of the ultrahigh-energy cosmic rays

2000

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“…Composition studies have also given indications that there is a change to light element composition for energies above ∼ 10 18 eV [3] although this conclusion is model dependent to some extent [2]. Also the small anisotropy ( 4%) of 10 18 eV cosmic rays in the direction of the galactic anticenter detected with AGASA disappears at higher energies [4].…”

Section: High Energy Cosmic Raysmentioning

confidence: 99%

Astroparticle physics: The high energy tail of the cosmic ray spectrum

Zas

2001

Nuclear Physics B - Proceedings Supplements

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“…The unambiguous determination of the existence of this anisotropic signal in the experimental data, and its astrophysical interpretation, is a fundamental challenge in the study of ultra high energy cosmic rays (UHECR) and is not free from controversies. The AGASA experiment reported [2] an interesting result claiming a 4.5σ excess at energies in the vicinity of ∼ 10 18 eV. Although AGASA was located in the Northern Hemisphere and the Galactic Center was out of its field of * gustavo.medinatanco@nucleares.unam.mx view, the anisotropy signal was located at low galactic latitudes and seemed to point to the general direction of the Galactic Center.…”

Section: Introductionmentioning

confidence: 99%

The Galactic Center as a point source of neutrons at EeV energies

Medina‐Tanco¹,

Krone-Martins²

2007

Nuclear Physics B - Proceedings Supplements

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The central region of our Galaxy is a very peculiar environment, containing magnetic fields in excess of 100 mG and gas densities reaching ∼ 10 4 cm −3 . This region was observed as a strong source of GeV and TeVs gammas, what suggests that a mechanism of proton-neutron conversion could be taking place therein. We propose that the Galactic Center must also be a source of EeV neutrons due to the conversion of ultra high energy cosmic ray protons into neutrons via p-p interactions inside this region. This scenario should be falsifiable by the Pierre Auger Observatory after a few years of full exposure.

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The anisotropy of cosmic ray arrival directions around 1018 eV

Cited by 214 publications

References 9 publications

Observations and implications of the ultrahigh-energy cosmic rays

Observations and implications of the ultrahigh-energy cosmic rays

Astroparticle physics: The high energy tail of the cosmic ray spectrum

The Galactic Center as a point source of neutrons at EeV energies

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