Discovery of Highly Obscured Galaxies in the Zone of Avoidance

TL;DR

This paper reports the discovery of 25 previously unknown galaxies in the Zone of Avoidance using mid-infrared surveys, revealing large-scale structures and demonstrating the effectiveness of infrared methods for such detections.

Contribution

It introduces a systematic infrared survey approach that uncovers obscured galaxies and links large-scale structures across the Galactic plane.

Findings

25 new galaxies discovered in the Zone of Avoidance

Identified overdensities consistent with large-scale structure

Galaxies mostly at redshifts 0.01-0.05

Abstract

We report the discovery of twenty-five previously unknown galaxies in the Zone of Avoidance. Our systematic search for extended extra-galactic sources in the GLIMPSE and MIPSGAL mid-infrared surveys of the Galactic plane has revealed two overdensities of these sources, located around l ~ 47 and 55 degrees and |b| less than 1 degree in the Sagitta-Aquila region. These overdensities are consistent with the local large-scale structure found at similar Galactic longitude and extending from |b| ~ 4 to 40 degrees. We show that the infrared spectral energy distribution of these sources is indeed consistent with those of normal galaxies. Photometric estimates of their redshift indicate that the majority of these galaxies are found in the redshift range z = 0.01 - 0.05, with one source located at z = 0.07. Comparison with known sources in the local Universe reveals that these galaxies are located at similar overdensities in redshift space. These new galaxies are the first evidence of a bridge linking the large-scale structure between both sides of the Galactic plane at very low Galactic latitude and clearly demonstrate the feasibility of detecting galaxies in the Zone of Avoidance using mid-to-far infrared surveys.