Armando Di Matteo (Author), Andrej Filipčič (Author), J. P. Lundquist (Author), Samo Stanič (Author), Serguei Vorobiov (Author), Danilo Zavrtanik (Author), Marko Zavrtanik (Author), Lukas Zehrer (Author)

Abstract

The distribution of ultra-high-energy cosmic-ray arrival directions appears to be nearly isotropic except for a dipole moment of order 6×(E/10 EeV) per cent. Nonetheless, at the highest energies, as the number of possible candidate sources within the propagation horizon and the magnetic deflections both shrink, smaller-scale anisotropies might be expected to emerge. On the other hand, the flux suppression reduces the statistics available for searching for such anisotropies. In this work, we consider two different lists of candidate sources: a sample of nearby starburst galaxies and the 2MRS catalog tracing stellar mass within 250 Mpc. We combine surface-detector data collected at the Pierre Auger Observatory until 2020 and the Telescope Array until 2019, and use them to test models in which UHECRs comprise an isotropic background and a foreground originating from the candidate sources and randomly deflected by magnetic fields. The free parameters of these models are the energy threshold, the signal fraction, and the search angular scale. We find a correlation between the arrival directions of 11.8%+5.0%−3.1% of cosmic rays detected with E≥38 EeV by Auger or with E≳49 EeV by TA and the position of nearby starburst galaxies on a 15.5∘+5.3∘−3.2∘ angular scale, with a 4.2σ post-trial significance, as well as a weaker correlation with the overall galaxy distribution.

Keywords

Pierre Auger Observatory;Telescope Array;indirect detection;ultra-high energy;cosmic rays;surface detection;

Data

Language: English
Year of publishing:
Typology: 1.08 - Published Scientific Conference Contribution
Organization: UNG - University of Nova Gorica
UDC: 539.1
COBISS: 166977027 Link will open in a new window
ISSN: 1824-8039
Views: 24
Downloads: 0
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Other data

Type (COBISS): Not categorized
Pages: str. 1-13
Chronology: 2022
DOI: 10.22323/1.395.0308
ID: 20033955
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