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UHECR arrival directions in the latest data from the original Auger and TA surface detectors and nearby galaxies

Di Matteo, A.; Anchordoqui, L.; Bister, T.; Biteau, J.; Caccianiga, L.; De Almeida, R.; Deligny, O.; Giaccari, U.; Harari, D.; Kim, J.; Kuznetsov, M.; Maris, I.; Rubtsov, G.; Tinyakov, P.; Troitsky, S.; Urban, F.; Abreu, P.; Aglietta, M.; Albury, J. M.; ... mehr


The distribution of ultra-high-energy cosmic-ray arrival directions appears to be nearly isotropic except for a dipole moment of order $6 \times (E/10~\mathrm{EeV})$ 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 $11.8\%_{-3.1\%}^{+5.0\%}$ of cosmic rays detected with $E \ge 38~\mathrm{EeV}$ by Auger or with $E \gtrsim 49~\mathrm{EeV}$ by TA and the position of nearby starburst galaxies on a ${15.5^\circ}_{-3.2^\circ}^{+5.3^\circ}$ angular scale, with a 4.2σ post-trial significance, as well as a weaker correlation with the overall galaxy distribution.

Verlagsausgabe §
DOI: 10.5445/IR/1000156092
Veröffentlicht am 02.03.2023
DOI: 10.22323/1.395.0308
Zitationen: 2
Zitationen: 9
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Astroteilchenphysik (IAP)
Institut für Prozessdatenverarbeitung und Elektronik (IPE)
Publikationstyp Proceedingsbeitrag
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 1824-8039
KITopen-ID: 1000156092
HGF-Programm 51.13.03 (POF IV, LK 01) Kosmische Strahlung Auger
Erschienen in 37th International Cosmic Ray Conference (ICRC2021): 12–23 July 2021, Berlin, Germany – Online
Veranstaltung 37th International Cosmic Ray Conference (ICRC 2021), Online, 12.07.2021 – 23.07.2021
Verlag Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Seiten Art.-Nr.: 308
Serie Proceedings of Science (PoS) ; 395
Nachgewiesen in Dimensions
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