PoS - Proceedings of Science
Volume 395 - 37th International Cosmic Ray Conference (ICRC2021) - CRI - Cosmic Ray Indirect
Extremely high energy (E > 10^{20} eV) cosmic rays: observations and potential sources
R. Hnatyk and V. Voitsekhovskyi*
Full text: pdf
Pre-published on: July 30, 2021
Published on: March 18, 2022
The search for sources of ultra-high energy cosmic rays
(UHECR, $E > 10^{18}$ eV) remains one of the advanced tasks in high
energy astrophysics. The observed high degree of isotropy of the UHECR
intensity due to impact of extragalactic and Galactic magnetic fields,
together with a significant uncertainty in their chemical composition (atomic masses)
due to indirect detection, don’t allow to link observed events to their sources
and to establish acceleration mechanisms.
To reduce the effects of deflection in magnetic fields and composition uncertainty,
we consider the most energetic tail of UHECR - rare extremely high energy cosmic
rays (EHECR, $E>10^{20}$ eV). Strongly energy-depended loss length of UHECR -
GZK-effect at $E>10^{19.5}$ eV further reduces the energy loss horizon of $E>10^{20.5}$ eV EHECR to a few Mpc level, favoring only protons and Fe group nuclei with $\sim$10 Mpc level.
Event-by-event reconstruction of EHECR trajectories in Galactic and extragalactic
magnetic fields opens up a possibility to discover their close to us sources.
We collect the existing data of EHECR detections at Fly's Eye (1 event),
Pierre Auger Observatory (PAO, 14 events after $k=1.2$ energy calibraion )
and Telescope Array (TA, 22 events) and identify their potential sources at
distances, restricted by energy loss horizon to 30-50 Mpc, among extragalactic (active galaxy nuclei,
starburst galaxies) and Galactic (magnetars) candidates.
The most promising candidates are Hypernovae with millisecond pulsar/magnetar,
giant flares of magnetars, Kilonovae (NS-NS mergers), tidal disruption events
etc. accompanied by (mildly) relativistic jets with close to the Earth directions.
DOI: https://doi.org/10.22323/1.395.0464
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