Galaxy And Mass Assembly: Galaxy Zoo spiral arms and star formation rates

TL;DR

This study uses Galaxy Zoo classifications to analyze how the number of spiral arms in galaxies correlates with star formation rates, revealing that galaxies with fewer arms tend to have higher star formation efficiencies.

Contribution

It is the first large-scale analysis linking spiral arm number with star formation properties using citizen science data from GAMA and Galaxy Zoo.

Findings

Galaxies with fewer spiral arms have lower stellar masses.

Galaxies with fewer spiral arms have higher specific star formation rates.

More spiral arms are associated with higher stellar masses and lower star formation efficiency.

Abstract

Understanding the effect spiral structure has on star formation properties of galaxies is important to completing our picture of spiral structure evolution. Previous studies have investigated connections between spiral arm properties with star formation, but the effect that the number of spiral arms has on this process is unclear. Here we use the Galaxy and Mass Assembly (GAMA) survey paired with the citizen science visual classifications from the Galaxy Zoo project to explore galaxies' spiral arm number and how it connects to the star formation process. We use the votes from the GAMA-KiDS GalaxyZoo classification to investigate the link between spiral arm number with stellar mass, star formation rate, and specific star formation rate. We find that galaxies with fewer spiral arms have lower stellar masses and higher sSFRs, while those with more spiral arms tend toward higher stellar masses and lower sSFRs, and conclude that galaxies are less efficient at forming stars if they have more spiral arms. We note how previous studies' findings may indicate a cause for this connection in spiral arm strength or opacity.