Galaxy Zoo: Clump Scout -- Design and first application of a two-dimensional aggregation tool for citizen science

TL;DR

Galaxy Zoo: Clump Scout is a citizen science project that uses a statistical aggregation framework to identify star-forming clumps in galaxy images, providing reliable data for galaxy evolution studies.

Contribution

We developed a novel statistical aggregation framework for citizen science annotations that estimates clump locations, volunteer skill levels, and false-positive probabilities.

Findings

Identified 128,100 potential clumps in 44,126 galaxies.

Aggregated over 3.5 million annotations from nearly 21,000 volunteers.

Provided a publicly available software framework for future analyses.

Abstract

Galaxy Zoo: Clump Scout is a web-based citizen science project designed to identify and spatially locate giant star forming clumps in galaxies that were imaged by the Sloan Digital Sky Survey Legacy Survey. We present a statistically driven software framework that is designed to aggregate two-dimensional annotations of clump locations provided by multiple independent Galaxy Zoo: Clump Scout volunteers and generate a consensus label that identifies the locations of probable clumps within each galaxy. The statistical model our framework is based on allows us to assign false-positive probabilities to each of the clumps we identify, to estimate the skill levels of each of the volunteers who contribute to Galaxy Zoo: Clump Scout and also to quantitatively assess the reliability of the consensus labels that are derived for each subject. We apply our framework to a dataset containing 3,561,454 two-dimensional points, which constitute 1,739,259 annotations of 85,286 distinct subjects provided by 20,999 volunteers. Using this dataset, we identify 128,100 potential clumps distributed among 44,126 galaxies. This dataset can be used to study the prevalence and demographics of giant star forming clumps in low-redshift galaxies. The code for our aggregation software framework is publicly available at: https://github.com/ou-astrophysics/BoxAggregator