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On the Anisotropy of E0 >= 5.5$times$1019 eV Cosmic Rays according to Data of the Pierre Auger Collaboration

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 نشر من قبل Alexander Glushkov
 تاريخ النشر 2012
  مجال البحث فيزياء
والبحث باللغة English
 تأليف A.V. Glushkov




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The Pierre Auger Collaboration discovered, in a solid angle of radius about 18degree, a local group of cosmic rays having energies in the region E0 geq 5.5times1019 eV and coming from the region of the Gen A radio galaxy, whose galactic coordinates are lG = 309.5degree and bG = 19.4degree. Near it, there is the Centaur supercluster of galaxies, its galactic coordinates being lG = 302.4degree and bG = 21.6degree. It is noteworthy that the Great Attractor, which may have a direct bearing on the observed picture, is also there.

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We report a measurement of the energy spectrum of cosmic rays above $2.5{times} 10^{18}$ eV based on $215,030$ events. New results are presented: at about $1.3{times} 10^{19}$ eV, the spectral index changes from $2.51 pm 0.03 textrm{ (stat.)} pm 0.05 textrm{ (sys.)}$ to $3.05 pm 0.05 textrm{ (stat.)}pm 0.10textrm{ (sys.)}$, evolving to $5.1pm0.3textrm{ (stat.)} pm 0.1textrm{ (sys.)}$ beyond $5{times} 10^{19}$ eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above $5{times} 10^{18}$ eV is $(5.66 pm 0.03 textrm{ (stat.)} pm 1.40 textrm{ (sys.)} ) {times} 10^{53}~$erg Mpc$^{-3}$.
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122 - A.V. Glushkov 2012
Results are presented that were obtained by analysing the arrival directions of E0 > 8x10**18 eV primary cosmic rays recorded at the Yakutsk array over the period between 1974 and 2003 and at the SUGAR array (Australia). The greatest primary cosmic r ay flux is shown to arrive from the region of visible intersection of the planes of the Galaxy and the Supergalaxy (local supercluster of galaxies) at a galactic longitude of about 137 degres. On a global scale, the lowest temperature of the cosmic microwave background is typical of this region.
We report a measurement of the energy spectrum of cosmic rays for energies above $2.5 {times} 10^{18}~$eV based on 215,030 events recorded with zenith angles below $60^circ$. A key feature of the work is that the estimates of the energies are indepen dent of assumptions about the unknown hadronic physics or of the primary mass composition. The measurement is the most precise made hitherto with the accumulated exposure being so large that the measurements of the flux are dominated by systematic uncertainties except at energies above $5 {times} 10^{19}~$eV. The principal conclusions are: (1) The flattening of the spectrum near $5 {times} 10^{18}~$eV, the so-called ankle, is confirmed. (2) The steepening of the spectrum at around $5 {times} 10^{19}~$eV is confirmed. (3) A new feature has been identified in the spectrum: in the region above the ankle the spectral index $gamma$ of the particle flux ($propto E^{-gamma}$) changes from $2.51 pm 0.03~{rm (stat.)} pm 0.05~{rm (sys.)}$ to $3.05 pm 0.05~{rm (stat.)} pm 0.10~{rm (sys.)}$ before changing sharply to $5.1 pm 0.3~{rm (stat.)} pm 0.1~{rm (sys.)}$ above $5 {times} 10^{19}~$eV. (4) No evidence for any dependence of the spectrum on declination has been found other than a mild excess from the Southern Hemisphere that is consistent with the anisotropy observed above $8 {times} 10^{18}~$eV.
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