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Browsing by Author "Petrov, Yevgeniy, author"

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    Constraints on the galactic magnetic field with two-point cumulative autocorrelation function
    (Colorado State University. Libraries, 2012) Petrov, Yevgeniy, author; Harton, John L., advisor; Mostafá, Miguel A., committee member; Berger, Bruce, committee member; Burns, Patrick J., committee member
    The fact that ultra high energy cosmic rays are charged particles complicates identication of their sources due to deflections by the intervening cosmic magnetic fields. The information about the fields is encoded in the amount of deflection experienced by a charged particle. Unfortunately, the positions of sources are unknown as is the structure of the magnetic field. However, it is possible to deduce the most favorable galactic magnetic field by examining the parameter space of different models of the galactic magnetic field. The method presented in this work is valid under some plausible assumptions, such as extragalactic origin of the UHECR, pure protonic composition above 50 EeV and sufficiently weak randomly oriented galactic and extragalactic components of the magnetic field. I use a two point cumulative autocorrelation function combined with the backtracking method to find regions in the parameter space that are compatible with statistically significant clustering on the extragalactic sky. This approach is independent of any catalog of sources. The ratio between the number of pairs within a certain angular window at the Earth sky and at the extragalactic sky after backtracking serves to indicate focusing or de-focusing properties of a particular field configuration. The results suggest that among several tested fields, the Harari-Mollerach-Roulet model with a bi-symmetric spiral and even vertical symmetry favors clustering of arrival directions at the extragalactic sky with the probability of 2.5% being from an isotropic distribution. Addition of the toroidal halo field improves clustering for the Harari-Mollerach-Roulet field for both bi-symmetric and axisymmetric spirals with even vertical symmetry, and the isotropic probabilities are 2.5% and 5.3% correspondingly. The bi-symmetric and axisymmetric spirals with odd vertical symmetry are disfavored, as well as the models with annular structure.