McKinley, BenjaminYang, RLopez-Caniego, MBriggs, FranklinHurley-Walker, NatashaWayth, RandallOffringa, AndreCrocker, RolandBernardi, GianniProcopio, P.Gaensler, B MTingay, S.J.Waterson, MarkBhat, N.D.R.Lonsdale, C. J.2018-11-292018-11-290035-8711http://hdl.handle.net/1885/152598We present new low-frequency observations of the nearby radio galaxy Fornax A at 154 MHz with the Murchison Widefield Array, microwave flux-density measurements obtained from WMAP and Planck data, and γ -ray flux densities obtained from Fermi data. 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 1510 MHz 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 γ -ray emission. A standard leptonic model for the production of both the X-rays and γ -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 γ -rays are produced primarily by hadronic processes confined to the filamentary structures of the Fornax A lobes. Key words: galaxies: active – galaxies: individual: NGC1316 – radio continuum: galaxiesapplication/pdf201510.1093/mnras/stu23102018-11-29