We generalize the maximum likelihood-type method used to study cross-correlations between a catalog of candidate astrophysical sources and ultrahigh energy cosmic rays (UHECRs), to allow for differing source luminosities. The new method is applicable to any sparse dataset such as UHE gamma rays or astrophysical neutrinos. Performance of the original and generalized techniques is evaluated in simulations of various scenarios. Applying the new technique to data, we find an excess correlation of about nine events between HiRes UHECRs and known BLLacs, with a 6 × 10 -5 probability of such a correlation arising by chance.
- High energy photons
- Ultra high energy cosmic rays
- Ultra high energy photons and neutrinos
ASJC Scopus subject areas
- Astronomy and Astrophysics