Intervenant : Brian Baughman (University of Maryland)
Résumé : "The arrival directions of ultra-high energy cosmic rays (UHECRs) are imprinted with information on the magnetic fields through which they pass. This information can be hidden within the resolution of the observing instruments, but for deflections which are large compared to the angular resolution of the detector this information can be accessed. The Galactic magnetic field, locally observed to be on the order of a few $\mu$G, is sufficiently strong to induce large (on the order of a degree) deflections in the arrival directions of UHECRs regardless of composition. The Field Scan Method has been developed to use that information to find hypotheses which improve the correlation between proposed sources beyond that which would be expected from an isotropic observation. The hypotheses specify composition, source distribution, and a magnetic field model. When tested with the Field Scan Method hypotheses which do little to improve the correlation between proposed sources and backtracked UHECR trajectories are suppressed while those hypotheses which do improve the correlations are highlighted. This method can be used with UHECR data from UHECR detectors such as the Pierre Auger Observatory to find Galactic magnetic field models which more accurately represent reality. The method will be described and interpretations of its results will be discussed."