Ultraviolet Luminosity Density of the Universe During the Epoch of Reionization

TL;DR

This study measures the ultraviolet luminosity density during the epoch of reionization using Hubble data, revealing significant faint galaxy populations that contributed to early universe reionization.

Contribution

It provides the first measurement of UV luminosity density at z > 8 through spatial fluctuation analysis of deep sky surveys.

Findings

UV luminosity density at z > 8 is approximately 27.4 erg s$^{-1}$ Hz$^{-1}$ Mpc$^{-3}$

Faint primeval galaxies below current detection thresholds significantly contributed to reionization

Spatial fluctuation analysis can probe early universe galaxy populations

Abstract

The spatial fluctuations of the extragalactic background light trace the total emission from all stars and galaxies in the Universe. A multi-wavelength study can be used to measure the integrated emission from first galaxies during reionization when the Universe was about 500 million years old. Here we report arcminute-scale spatial fluctuations in one of the deepest sky surveys with the Hubble Space Telescope in five wavebands between 0.6 and 1.6 $\mu$m. We model-fit the angular power spectra of intensity fluctuation measurements to find the ultraviolet luminosity density of galaxies at $z$ > 8 to be $\log \rho_{\rm UV} = 27.4^{+0.2}_{-1.2}$ erg s$^{-1}$ Hz$^{-1}$ Mpc$^{-3}$ $(1\sigma)$. This level of integrated light emission allows for a significant surface density of fainter primeval galaxies that are below the point source detection level in current surveys.