Abstract
Evidence of supergalactic structure of multiplets has been found for ultra-high energy cosmic rays (UHECR) with energies above 1019 eV using 7 years of data from the Telescope Array (TA) surface detector. The tested hypothesis is that UHECR sources, and intervening magnetic fields, may be correlated with the supergalactic plane, as it is a fit to the average matter density within the GZK horizon. This structure is measured by the average behavior of the strength of intermediate-scale correlations between event energy and position (multiplets). These multiplets are measured in wedge-like shapes on the spherical surface of the fieldof-view to account for uniform and random magnetic fields. The evident structure found is consistent with toy-model simulations of a supergalactic magnetic sheet and the previously published Hot/Coldspot results of TA. The post-trial probability of this feature appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be ~4.5σ.
Highlights
The supergalactic plane (SGP) is the average matter distribution of the local universe up to a distance of ∼200 Mpc [1]
To calculate the data significance of a supergalactic structure of multiplets the analysis described above is applied, both to the data, and the isotropic Monte Carlo (MC) sets
This is the expectation for a grid point that happens to be near a ultra-high energy cosmic rays (UHECR) source of magnetically scattered events
Summary
The supergalactic plane (SGP) is the average matter distribution of the local universe up to a distance of ∼200 Mpc (a large percentage is within the GZK cutoff of 100 Mpc) [1]. It has been shown that ∼90% of the baryonic mass of the universe is between galaxies of which ∼40% is warm-hot protons outside gas clouds [3] This may allow the formation of intra-galactic large scale magnetic fields ([4],[5]). Previous energy-position correlation studies have not had significant results ([6],[7],[8]) These multiplet searches for significant small scale magnetic deflection patterns included scanned parameters chosen by assumed magnetic field models and compositions. This analysis uses intermediate-scale energy-position correlations to look for significant large scale magnetic structure and minimal assumptions are made regarding particular magnetic field models or composition
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