Radio phoenixes are extended filamentary sources in the intracluster medium (ICM) of galaxy clusters, associated with fossil radio lobes. Their soft, concave-curved spectra, commonly attributed to aged relativistic electrons recently accelerated/compressed, are shown to approach a power-law at high frequencies. Moreover, secondary $e^{\pm }$ produced by a pure power-law spectrum of relativistic ions explain all phoenix observations with only three free parameters. Hadronic phoenixes require strong magnetization and, for high-curvature, also $e^{\pm }$ heating, by a factor $\gtrsim 15$ if at ICM pressure.

Close

PrevNext

View figure in article

• Cosmic rays & astroparticles
• Electromagnetic radiation astronomy
• Large scale structure of the Universe
• Radio, microwave, & sub-mm astronomy
• Galaxy clusters
• Astrophysical electromagnetic fields