AKARI near-infrared background fluctuations arise from normal galaxy populations

Abstract

We show that measurements of the fluctuations in the near-infrared background (NIRB) from the AKARI satellite can be explained by faint galaxy populations at low redshifts. We demonstrate this using reconstructed images from deep galaxy catalogues (Hawk-I UDS/GOODS Survey and S-Cosmic Assembly Deep Near-Infrared Extragalactic Legacy Survey) and two independent galaxy population models. In all cases, we find that the NIRB fluctuations measured by AKARI are consistent with faint galaxies and there is no need for a contribution from unknown populations. We find that a steep Rayleigh-Jeans spectrum for the underlying sources is not required as previously reported. The apparent Rayleigh-Jeans spectrum at large angular scales is likely a consequence of galaxies being removed systematically to deeper levels in the longer wavelength channels.