Fuzzy Galaxies or Cirrus? Decomposition of Galactic Cirrus in Deep Wide-Field Images

TL;DR

This paper introduces a new photometric technique to decompose Galactic cirrus in deep wide-field images, enabling better separation of dust emission from background sources and improving the detection of faint galaxies.

Contribution

The paper presents a novel method combining morphological extraction and color constraints from Planck dust models for Galactic cirrus decomposition.

Findings

Effective cirrus removal enhances detection of low surface brightness galaxies.

The method achieves high radiometric precision in measuring optical DGL intensities.

Performance metrics show the technique's robustness across different sky conditions.

Abstract

Diffuse Galactic cirrus, or Diffuse Galactic Light (DGL), can be a prominent component in the background of deep wide-field imaging surveys. The DGL provides unique insights into the physical and radiative properties of dust grains in our Milky Way, and it also serves as a contaminant on deep images, obscuring the detection of background sources such as low surface brightness galaxies. However, it is challenging to disentangle the DGL from other components of the night sky. In this paper, we present a technique for the photometric characterization of Galactic cirrus, based on (1) extraction of its filamentary or patchy morphology and (2) incorporation of color constraints obtained from Planck thermal dust models. Our decomposition method is illustrated using a $\sim$10 deg$^2$ imaging dataset obtained by the Dragonfly Telephoto Array, and its performance is explored using various metrics which characterize the flatness of the sky background. As a concrete application of the technique, we show how removal of cirrus allows low surface brightness galaxies to be identified on cirrus-rich images. We also show how modeling the cirrus in this way allows optical DGL intensities to be determined with high radiometric precision.