Discovery of localized regions of excess 10-TeV cosmic rays

A. A. Abdo, B. Allen, T. Aune, D. Berley, E. Blaufuss, S. Casanova, C. Chen, B. L. Dingus, R. W. Ellsworth, L. Fleysher, R. Fleysher, M. M. Gonzalez, J. A. Goodman, C. M. Hoffman, P. H. Hüntemeyer, B. E. Kolterman, C. P. Lansdell, J. T. Linnemann, J. E. McEnery, A. I. MincerP. Nemethy, D. Noyes, J. Pretz, J. M. Ryan, P. M.Saz Parkinson, A. Shoup, G. Sinnis, A. J. Smith, G. W. Sullivan, V. Vasileiou, G. P. Walker, D. A. Williams, G. B. Yodh

Research output: Contribution to journalArticlepeer-review

212 Scopus citations

Abstract

The 7 year data set of the Milagro TeV observatory contains 2.2×1011 events of which most are due to hadronic cosmic rays. These data are searched for evidence of intermediate scale structure. Excess emission on angular scales of ∼10° has been found in two localized regions of unknown origin with greater than 12σ significance. Both regions are inconsistent with pure gamma-ray emission with high confidence. One of the regions has a different energy spectrum than the isotropic cosmic-ray flux at a level of 4.6σ, and it is consistent with hard spectrum protons with an exponential cutoff, with the most significant excess at ∼10TeV. Potential causes of these excesses are explored, but no compelling explanations are found.

Original languageEnglish (US)
Article number221101
JournalPhysical Review Letters
Volume101
Issue number22
DOIs
StatePublished - Nov 24 2008
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy

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