Integrated Galaxy Light from Stacking $10^5$ Random Pointings in the Dark Energy Survey Data

TL;DR

This paper introduces a stacking method to measure integrated galaxy light from DES data, providing consistent results without foreground removal, and highlighting the technique's advantages and limitations.

Contribution

The paper presents a novel stacking approach to measure integrated galaxy light directly from survey data, avoiding foreground subtraction and enabling new insights into diffuse light.

Findings

Measured IGL values in multiple bands consistent with previous studies

Stacking reduces sensitivity to local backgrounds but not large-scale diffuse light

Method provides a new way to analyze galaxy light without foreground removal

Abstract

We present a new technique for measuring the integrated galaxy light (IGL) with stacked image data from the Dark Energy Survey (DES). We extract $1\times1$ arcminute cutouts from nearly 100,000 randomly selected positions in the g, r, i, z, and Y bands from the DES data release 2 (DR2) maps. We generate source catalogs and masks for each cutout and the images are subsequently stacked to generate deep images of the sky both with and without sources. The IGL is then calculated by taking the difference in average brightness between stacks that contain galaxies and stacks in which galaxies have been masked. We find IGL values of $g = 4.27 \pm 0.28, r = 6.97 \pm 0.42, i = 8.66 \pm 0.53, z = 10.16 \pm 0.7,$ and $Y = 13.78 \pm 2.35$ nW/m$^2$/sr. These measurements, which require no foreground estimation or removal, are in agreement with previously reported IGL values derived from galaxy number counts and other methods. This stacking technique reduces the sensitivity to diffuse local backgrounds but is not sensitive to large-scale diffuse extragalactic background light.