On the Origin of Near-Infrared Extragalactic Background Light Anisotropy

TL;DR

This study presents new measurements of near-infrared EBL anisotropy, revealing fluctuations mainly due to intra-halo light, which suggest a significant photon energy contribution from faint, extended sources beyond known galaxy populations.

Contribution

It provides novel anisotropy measurements at 1.1 and 1.6 micrometers, demonstrating that intra-halo light explains observed fluctuations better than primordial galaxies or black holes.

Findings

Fluctuations exceed known galaxy contributions.

Intra-halo light accounts for most anisotropy.

EBL intensity is comparable to galaxy background.

Abstract

Extragalactic background light (EBL) anisotropy traces variations in the total production of photons over cosmic history, and may contain faint, extended components missed in galaxy point source surveys. Infrared EBL fluctuations have been attributed to primordial galaxies and black holes at the epoch of reionization (EOR), or alternately, intra-halo light (IHL) from stars tidally stripped from their parent galaxies at low redshift. We report new EBL anisotropy measurements from a specialized sounding rocket experiment at 1.1 and 1.6 micrometers. The observed fluctuations exceed the amplitude from known galaxy populations, are inconsistent with EOR galaxies and black holes, and are largely explained by IHL emission. The measured fluctuations are associated with an EBL intensity that is comparable to the background from known galaxies measured through number counts, and therefore a substantial contribution to the energy contained in photons in the cosmos.