Overlap Zoo Beta: A Catalogue of ~800 Occulting Pairs in the DESI Legacy Survey using Citizen Science

TL;DR

This paper presents a new catalogue of approximately 800 overlapping galaxy pairs identified through citizen science in the DESI Legacy Survey, enabling detailed dust attenuation studies and supporting automated classification methods.

Contribution

The study introduces a large, publicly available catalogue of overlapping galaxy pairs identified via citizen science, expanding resources for dust attenuation research and machine learning applications.

Findings

Catalogue contains ~800 overlapping galaxy pairs.

Enables detailed dust attenuation analysis.

Supports development of automated identification techniques.

Abstract

Overlapping galaxies, in which a foreground galaxy partially overlaps a background galaxy, offer a unique opportunity to measure dust attenuation, a key nuisance parameter in galaxy studies, empirically and in great detail by modelling the light of both the foreground and background galaxy and inferring the missing light in the overlapping region. However, the current catalogue of overlapping pairs is relatively limited in number compared to catalogues dedicated to individual galaxies. Expanding this catalogue is not only a necessity to facilitate further detailed dust studies beyond the few limited studies conducted thus far, but also to improve pair-to-pair variance and support automated identification through machine learning techniques. To achieve this, we utilise galaxies classified as "overlapping" from Galaxy Zoo DECaLS (GZD-1, -2, and -5), along with images from Data Release 10 (DR10) of the DESI Legacy Survey, in our individual citizen science project to classify these pairs directly using volunteers. This new catalogue will not only provide a wealth of targets for future dust studies but will also contribute to a deeper understanding of these pairs and dust as a whole.