The 7 year data set of the Milagro TeV observatory contains 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 has been found in two localized regions of unknown origin with greater than 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 , and it is consistent with hard spectrum protons with an exponential cutoff, with the most significant excess at . Potential causes of these excesses are explored, but no compelling explanations are found.
- Received 23 January 2008
- Revised 29 September 2008
- Published 24 November 2008
© 2008 The American Physical Society