An updated estimate of the cosmic radio background and implications for ultra-high-energy photon propagation

Research output: Contribution to journalArticlepeer-review

  • Authors:
  • Iuliana-Camelia Nitu
  • Harry Bevins
  • Justin Bray
  • Anna Scaife


We present an updated estimate of the cosmic radio background (CRB) and the corresponding attenuation lengths for ultra-high energy photons. This new estimate provides associated uncertainties as a function of frequency derived from observational constraints on key physical parameters. We also present the expected variation in the spectrum of the CRB as a function of these parameters, as well as accounting for the expected variation in spectral index among the population of radio galaxies. The new estimate presented in this work shows better agreement with observational constraints from radio source-count measurements than previous calculations. In the energy regime where we expect cosmogenic photons dominantly attenuated by the CRB, our calculation of the attenuation length differs from previous estimates by a factor of up to 3, depending on energy and the specific model for comparison. These results imply a decrease in the expected number of cosmogenic photons with energies ~10^19 – 10^20 eV.

Bibliographical metadata

Original languageEnglish
JournalAstroparticle Physics
Issue number102532
Publication statusPublished - Mar 2021