AKARI near-infrared background fluctuations arise from normal galaxy populations

TL;DR

This study demonstrates that near-infrared background fluctuations observed by AKARI are fully explained by faint, low-redshift galaxy populations, negating the need for unknown sources and challenging previous spectral assumptions.

Contribution

The paper shows that AKARI NIRB fluctuations can be explained by faint galaxy populations using reconstructed images and models, without invoking unknown sources or steep spectra.

Findings

NIRB fluctuations are consistent with faint galaxy populations.

No evidence for a steep Rayleigh-Jeans spectrum in the sources.

Systematic removal of galaxies affects the observed spectrum.

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 catalogs (HUGS/S-CANDELS) 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 no evidence for a steep Rayleigh-Jeans spectrum for the underlying sources 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.