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1.
Search for energy dependent patterns in the arrival direction of cosmic rays at the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Tobias Winchen, 2015, published scientific conference contribution

Abstract: Energy-dependent patterns in the arrival directions of cosmic rays are expected from deflections in galactic and extragalactic magnetic fields. We report on searches for such patterns in the data of the surface detector of the Pierre Auger Observatory at energies above E = 5 EeV in regions within approximately 15◦ around events with energy E > 60 EeV. No significant patterns are found with this analysis which can be used to constrain parameters in propagation scenarios.
Found in: ključnih besedah
Summary of found: ...expected from deflections in galactic and extragalactic magnetic fields. We report on searches for...
Keywords: ultra-high energy cosmic rays galactic and extragalactic magnetic fields magnetic deflection patterns Pierre Auger Observatory
Published: 02.03.2016; Views: 3146; Downloads: 182
.pdf Fulltext (1019,52 KB)

2.
Search for Anisotropy in the Ultra High Energy Cosmic Ray Spectrum using the Telescope Array Surface Detector
J. P. Lundquist, R.U. Abbasi, 2017, other component parts

Abstract: The Telescope Array (TA) experiment is located in the western desert of Utah, USA, and observes ultra high energy cosmic rays (UHECRs) in the Northern hemisphere. At the highest energies, E>10~EeV, the shape of cosmic ray energy spectrum may carry an imprint of the source density distribution along the line of sight different in different directions of the sky. In this study, we search for such directional variations in the shape of the energy spectrum using events observed with the Telescope Array's surface detector. We divide the TA field of view into two nearly equal-exposure regions: the "on-source" region which we define as ±30∘ of the supergalactic plane containing mostly nearby structures, and the complementary "off-source" region where the sources are further away on average. We compare the UHECR spectra in these regions by fitting them to the broken power law and comparing the resulting parameters. We find that the off-source spectrum has an earlier break at highest energies. The chance probability to obtain such or larger difference in statistically equivalent distributions is estimated as 6.2±1.1×10−4 (3.2σ) by a Monte-Carlo simulation. The observed difference in spectra is in a reasonable quantitative agreement with a simplified model that assumes that the UHECR sources trace the galaxy distribution from the 2MRS catalogue, primary particles are protons and the magnetic deflections can be neglected.
Found in: ključnih besedah
Summary of found: ...catalogue, primary particles are protons and the magnetic deflections can be neglected.... ...cosmic radiation: spectrum, cosmic radiation: energy spectrum, deflection: magnetic, numerical calculations: Monte Carlo, anisotropy...
Keywords: cosmic radiation: UHE, detector: surface, cosmic radiation: spectrum, cosmic radiation: energy spectrum, deflection: magnetic, numerical calculations: Monte Carlo, anisotropy
Published: 27.04.2020; Views: 1116; Downloads: 42
.pdf Fulltext (169,05 KB)

3.
Supergalactic Structure of Energy-Angle Correlations
P. Sokolsky, J. P. Lundquist, 2020, published scientific conference contribution

Abstract: Evidence for the supergalactic structure of multiplets (energy-angle correlations) has previously been shown using ultra-high energy cosmic ray (UHECR) data from Telescope Array (TA) with energies above 10^19 eV. The supergalactic deflection hypothesis (that UHECR sources and intervening magnetic fields are correlated) is measured by the all-sky behavior of the strength of intermediate-scale correlations. The multiplets are measured in spherical surface wedge bins of the field-of-view to account for uniform and random magnetic fields. The structure found is consistent with the previously published energy spectrum anisotropy results of TA and toy-model simulations of a supergalactic magnetic sheet. The 7 year data post-trial significance of this feature appearing by chance, on an isotropic sky, was found by Monte Carlo simulation to be ∼4σ. The analysis has now been applied to 10 years of data.
Found in: ključnih besedah
Summary of found: ...deflection hypothesis (that UHECR sources and intervening magnetic fields are correlated) is measured by the...
Keywords: Cosmic rays, UHECR, energy spectrum, magnetic deflection, large-scale structure, supergalactic, multiplets
Published: 27.04.2020; Views: 1085; Downloads: 43
.pdf Fulltext (1,66 MB)

4.
Supergalactic Structure of Multiplets with the Telescope Array Surface Detector
P. Sokolsky, J. P. Lundquist, 2019, published scientific conference contribution

Abstract: Evidence of supergalactic structure of multiplets has been found for ultra-high energy cosmic rays (UHECR) with energies above 10^19 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.
Found in: ključnih besedah
Summary of found: ...hypothesis is that UHECR sources, and intervening magnetic fields, may be correlated with the supergalactic...
Keywords: UHECR, cosmic rays, energy spectrum, anisotropy, large-scale structure, magnetic deflection
Published: 28.04.2020; Views: 1184; Downloads: 78
.pdf Fulltext (1,38 MB)

5.
Evidence of Intermediate-Scale Energy Spectrum Anisotropy in the Northern Hemisphere from Telescope Array
J. P. Lundquist, 2018, published scientific conference contribution

Abstract: Evidence of an energy dependent intermediate-scale anisotropy has been found in the arrival directions of ultra-high energy cosmic rays in the northern hemisphere, using 7 years of TA surface detector data. The previously reported ``hot spot" excess E ≥ 10^19.75 EeV is found to correspond to a deficit, or ``cold spot," of events for 10^19.2≤ E < 10^19.75 EeV. This feature suggests energy dependent magnetic deflection of cosmic-rays. The global post-trial significance of the energy spectrum deviation is found to be 3.74σ.
Found in: ključnih besedah
Summary of found: ...10^19.75 EeV. This feature suggests energy dependent magnetic deflection of cosmic-rays. The global post-trial significance...
Keywords: UHECR, cosmic rays, energy spectrum, anisotropy, magnetic deflection
Published: 28.04.2020; Views: 1122; Downloads: 38
.pdf Fulltext (4,87 MB)

6.
Telescope Array Hot/Coldspot Study – Intermediate Scale Anisotropy
J. P. Lundquist, published scientific conference contribution abstract

Abstract: Indications of energy dependent intermediate scale anisotropy has been found in the arrival directions of ultra high energy cosmic rays with energies above 20 EeV in the northern hemisphere, using 7 years of TA surface detector data. The previously reported “hotspot‘” excess for E>57 EeV is found to correspond to a deficit, or “coldspot ”, of events for energies 2057 EeV has a Li Ma statistical significance of 4.62σ, and the deficit for energies 20Found in: ključnih besedah
Summary of found: ...The hot/ coldspot feature suggests energy dependent magnetic deflection of the isotropic background and cosmic rays...
Keywords: cosmic rays, energy spectrum, anisotropy, magnetic deflection
Published: 28.04.2020; Views: 1079; Downloads: 0
.pdf Fulltext (2,25 MB)

7.
Energy-position correlation anisotropy of ultra-high energy cosmic rays with Telescope Array Data
J. P. Lundquist, published scientific conference contribution abstract

Abstract: Indication of an energy dependent intermediate-scale anisotropy has been found in the arrival directions of ultra-high energy cosmic rays with energies above 20 EeV in the northern hemisphere, using 7 years of TA surface detector data. The previously reported “hotspot“ excess for E>57 EeV is found to correspond to a deficit, or “coldspot“, of events for energies 2057 EeV has a Li-Ma statistical significance of 4.62σ, and the deficit for energies 20Found in: ključnih besedah
Summary of found: ...supergalactic plane. The hot/coldspot feature suggests energy dependent magnetic deflection of the isotropic background and cosmic-rays...
Keywords: UHECR, energy spectrum, anisotropy, magnetic deflection
Published: 29.04.2020; Views: 1081; Downloads: 0
.pdf Fulltext (1,84 MB)

8.
Evidence for a Supergalactic Structure of Magnetic Deflection Multiplets of Ultra-High Energy Cosmic Rays
J. P. Lundquist, R. Abbasi, 2020, original scientific article

Abstract: Evidence for a large-scale supergalactic cosmic ray multiplet (arrival directions correlated with energy) structure is reported for ultra-high energy cosmic ray (UHECR) energies above 10^19 eV using seven years of data from the Telescope Array (TA) surface detector and updated to 10 years. Previous energy-position correlation studies have made assumptions regarding magnetic field shapes and strength, and UHECR composition. Here the assumption tested is that, since the supergalactic plane is a fit to the average matter density of the local Large Scale Structure (LSS), UHECR sources and intervening extragalactic magnetic fields are correlated with this plane. This supergalactic deflection hypothesis is tested by the entire field-of-view (FOV) behavior of the strength of intermediate-scale energy-angle correlations. These multiplets are measured in spherical cap section bins (wedges) of the FOV to account for coherent and random magnetic fields. The structure found is consistent with supergalactic deflection, the previously published energy spectrum anisotropy results of TA (the hotspot and coldspot), and toy-model simulations of a supergalactic magnetic sheet. The seven year data post-trial significance of this supergalactic structure of multiplets appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be 4.19σ. The ten years of data post-trial significance is 4.09σ. Furthermore, the starburst galaxy M82 is shown to be a possible source of the TA Hotspot, and an estimate of the supergalactic magnetic field using UHECR measurements is presented.
Found in: ključnih besedah
Keywords: astroparticle physics, cosmic rays, UHECR, supergalactic plane, multiplets, magnetic deflection, large-scale structure of universe
Published: 19.05.2020; Views: 991; Downloads: 0
.pdf Fulltext (4,40 MB)

9.
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