The arrival directions of cosmic rays detected by the Pierre Auger Observatory ( Auger ) with energies above 39 EeV were recently reported to correlate with the positions of 23 nearby starburst galaxies ( SBGs ) : in their best-fit model , 9.7 % of the cosmic-ray flux originates from these objects and undergoes angular diffusion on a 12.9 ^ { \circ } scale .
On the other hand , some of the SBGs on their list , including the brightest one ( M82 ) , are at northern declinations outside the Auger field of view .
Data from detectors in the northern hemisphere would be needed to look for cosmic-ray excesses near these objects .
In this work , we tested the Auger best-fit model against data collected by the Telescope Array ( TA ) in a 9-year period , without trying to re-optimize the model parameters for our dataset in order not to introduce statistical penalties .
The resulting test statistic ( double log-likelihood ratio ) was -1.00 , corresponding to 1.1 \sigma significance among isotropically generated random datasets , and to -1.4 \sigma significance among ones generated assuming the Auger best-fit model .
In other words , our data is still insufficient to conclusively rule out either hypothesis .
The ongoing fourfold expansion of TA will collect northern hemisphere data with much more statistics , improving our ability to discriminate between different flux models .