Fornax A MWA 154MHz image

We also compile a comprehensive list of previously published images and flux-density measurements at radio, microwave and X-ray energies. A detailed analysis of the spectrum of Fornax A between 154 and 1510MHz reveals that both radio lobes have a similar spatially averaged spectral index, and that there exists a steep-spectrum bridge of diffuse emission between the lobes.

Taking the spectral index of both lobes to be the same, we model the spectral energy distribution of Fornax A across an energy range spanning 18 orders of magnitude, to investigate the origin of the X-ray and {gamma}-ray emission. A standard leptonic model for the production of both the X-rays and {gamma}-rays by inverse-Compton scattering does not fit the multiwavelength observations. Our results best support a scenario where the X-rays are produced by inverse-Compton scattering and the {gamma}-rays are produced primarily by hadronic processes confined to the filamentary structures of the Fornax A lobes.