2021/07/28 by Lukas Merten, Margot Boughelilba, Merten, Lukas +15
Engineering · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Particle Accelerators and Free-Electron Lasers #Particle accelerators and beam dynamics
paper · pdf · doi:10.48550/arxiv.2107.13278
openalex publication_date 2021/07/28 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
Fanaroff-Riley (FR) 0 radio galaxies form a low-luminosity extension to the\nwell-established ultra-high-energy cosmic-ray (UHECR) candidate accelerators\nFR-1 and FR-2 galaxies. Their much higher number density -- up to a factor five\ntimes more numerous than FR-1 with z\≤ 0.05 -- makes them good candidate\nsources for an isotropic contribution to the observed UHECR flux. Here, the\nacceleration and survival of UHECR in prevailing conditions of the FR-0\nenvironment are discussed.\n First, an average spectral energy distribution (SED) is compiled based on the\n\FR0CAT. These photon fields, composed of a jet and a host galaxy\ncomponent, form a minimal target photon field for the UHECR, which will suffer\nfrom electromagnetic pair production, photo-disintegration, photo-meson\nproduction losses, and synchrotron radiation. The two most promising\nacceleration scenarios based on Fermi-I order and gradual shear acceleration\nare discussed as well as different escape scenarios.\n When an efficient acceleration mechanism precedes gradual shear acceleration,≠.g., Fermi-I or others, FR-0 galaxies are likely UHECR accelerators. Gradual\nshear acceleration requires a jet Lorentz factor of \Γ>1.6, to be faster\nthan the corresponding escape. In less optimistic models, a contribution to the\ncosmic-ray flux between the knee and ankle is expected to be relatively\nindependent of the realized turbulence and acceleration.\n