An observational determination of the evolving extragalactic background light from the multiwavelength HST/CANDELS survey in the Fermi and CTA era

TL;DR

This paper presents a new, galaxy-data-based method to determine the evolving extragalactic background light (EBL) spectral energy distribution up to redshift 6, reducing uncertainties and aligning with cosmic observations.

Contribution

It introduces a novel approach using multiwavelength galaxy data from the CANDELS survey to accurately derive the EBL evolution and its uncertainties up to high redshifts.

Findings

EBL evolution derived up to redshift 6 consistent with galaxy surveys and gamma-ray observations.

The dataset includes approximately 150,000 galaxies, making it one of the most comprehensive multiwavelength studies.

Results support current models of star formation and galaxy evolution at high redshifts.

Abstract

The diffuse extragalactic background light (EBL) is formed by ultraviolet (UV), optical, and infrared (IR) photons mainly produced by star formation processes over the history of the Universe, and contains essential information about galaxy evolution and cosmology. Here, we present a new determination of the evolving EBL spectral energy distribution using a novel approach purely based on galaxy data aiming to reduce current uncertainties on the higher redshifts and IR intensities. Our calculations use multiwavelength observations from the UV to the far-IR of a sample of approximately 150,000 galaxies detected up to $z\sim 6$ in the five fields of the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) from the Hubble Space Telescope. This is one of the most comprehensive and deepest multi-wavelength galaxy datasets ever obtained. These unprecedented resources allow us to derive the overall EBL evolution up to $z\sim 6$ and its uncertainties. Our results agree with cosmic observables estimated from galaxy surveys and $\gamma$-ray attenuation such as monochromatic luminosity densities, including those in the far-IR, and star formation rate densities, also at the highest redshits. Optical depths from our EBL approximation, which will be robust at high redshifts and for $\gamma$ rays up to tens of TeV, will be reported in a companion paper.