Evidence for a Z < 8 Origin of the Source Subtracted Near Infrared Background

TL;DR

This study analyzes near-infrared background fluctuations to determine their origin, concluding that most of the power comes from galaxies at redshifts below 8, based on fluctuation ratios and spectral energy distribution modeling.

Contribution

It extends previous fluctuation analysis to 1.1 microns and uses spectral models to constrain the redshift range of sources contributing to the near-infrared background.

Findings

Fluctuation ratios are consistent with z<8 sources.

Predicted fluctuation power matches observations for z=0-12.

Power from z>13 galaxies exceeds observed levels.

Abstract

This letter extends our previous fluctuation analysis of the near infrared background at 1.6 microns to the 1.1 micron (F110W) image of the Hubble Ultra Deep field. When all detectable sources are removed the ratio of fluctuation power in the two images is consistent with the ratio expected for faint, z<8, sources, and is inconsistent with the expected ratio for galaxies with z>8. We also use numerically redshifted model galaxy spectral energy distributions for 50 and 10 million year old galaxies to predict the expected fluctuation power at 3.6 microns and 4.5 microns to compare with recent Spitzer observations. The predicted fluctuation power for galaxies at z = 0-12 matches the observed Spitzer fluctuation power while the predicted power for z>13 galaxies is much higher than the observed values. As was found in the 1.6 micron (F160W) analysis the fluctuation power in the source subtracted F110W image is two orders of magnitude below the power in the image with all sources present. This leads to the conclusion that the 0.8--1.8 micron near infrared background is due to resolved galaxies in the redshift range z<8, with the majority of power in the redshift range of 0.5--1.5.