Lukas Merten (Author), Margot Boughelilba (Author), Anita Reimer (Author), Paolo Da Vela (Author), Serguei Vorobiov (Author), Fabrizio Tavecchio (Author), Giacomo Bonnoli (Author), J. P. Lundquist (Author), Chiara Righi (Author)

Abstract

Fanaroff-Riley (FR) 0 radio galaxies compose a new class of radio galaxies, which are usually weaker but much more numerous than the well-established class of FR 1 and FR 2 galaxies. The latter classes have been proposed as sources of the ultra-high-energy cosmic rays (UHECRs) with energies reaching up to eV. Based on this conjecture, the possibility of UHECR acceleration and survival in an FR 0 source environment is examined in this work. In doing so, an average spectral energy distribution (SED) based on data from the FR 0 catalog (FR0CAT) is compiled. The resulting photon fields are used as targets for UHECRs, which suffer from electromagnetic pair production, photo-disintegration, photo-meson production losses, and synchrotron radiation. Multiple mechanisms are discussed to assess the UHECR acceleration probability, including Fermi-I order and gradual shear accelerations, and particle escape from the source region. This work shows that in a hybrid scenario, combining Fermi and shear accelerations, FR 0 galaxies can contribute to the observed UHECR flux, as long as where shear acceleration starts to dominate over escape. Even in less optimistic scenarios, FR 0s can be expected to contribute to the cosmic-ray flux between the knee and the ankle. Our results are relatively robust with respect to the realized magnetic turbulence model and the speed of the accelerating shocks.

Keywords

acceleration of particles;nonthermal radiation mechanisms;jets;active galaxies;cosmic rays;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UNG - University of Nova Gorica
UDC: 539.1
COBISS: 50457091 Link will open in a new window
ISSN: 0927-6505
Views: 1814
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Other data

URN: URN:SI:UNG
Pages: str. 1-22
Issue: ǂVol. ǂ128
Chronology: 2021
DOI: 10.1016/j.astropartphys.2021.102564
ID: 12535943
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