extending the zoo of candidate sites for UHECR acceleration
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 form a low-luminosity extension to the well-established ultra-high-energy cosmic-ray (UHECR) candidate accelerators FR-1 and FR-2 galaxies. Their much higher number density — up to a factor five times more numerous than FR-1 with z ≤ 0.05 — makes them good candidate sources for an isotropic contribution to the observed UHECR flux. Here, the acceleration and survival of UHECR in prevailing conditions of the FR-0 environment are discussed. First, an average spectral energy distribution (SED) is compiled based on the FR0CAT. These photon fields, composed of a jet and a host galaxy component, form a minimal target photon field for the UHECR, which will suffer from electromagnetic pair production, photo-disintegration, photo-meson production losses, and synchrotron radiation. The two most promising acceleration scenarios based on Fermi-I order and gradual shear acceleration are discussed as well as different escape scenarios. When an efficient acceleration mechanism precedes gradual shear acceleration, e.g., Fermi-I orothers, FR-0 galaxies are likely UHECR accelerators. Gradual shear acceleration requires a jet Lorentz factor of Gamma>1.6, to be faster than the corresponding escape. In less optimistic models, a contribution to the cosmic-ray flux between the knee and ankle is expected to be relatively independent of the realized turbulence and acceleration.

Keywords

jetted active galaxies;FR-0 radiogalaxies;ultra-high energy cosmic rays;cosmic ray acceleration;cosmic ray energy losses;

Data

Language: English
Year of publishing:
Typology: 1.08 - Published Scientific Conference Contribution
Organization: UNG - University of Nova Gorica
UDC: 539.1
COBISS: 73062147 Link will open in a new window
ISSN: 1824-8039
Views: 1389
Downloads: 0
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Other data

URN: URN:SI:UNG
Pages: str. 1-8
Chronology: 2022
ID: 13283802