Investigating Clumpy Galaxies in the Sloan Digital Sky Survey Stripe 82 using the Galaxy Zoo

TL;DR

This study analyzes local universe clumpy galaxies using Galaxy Zoo data, revealing properties similar to high-redshift clumps but challenging existing migration theories, suggesting different evolutionary processes.

Contribution

First large-scale, statistically significant analysis of local clumpy galaxies, providing new insights into their properties and evolution.

Findings

Local clumps have similar properties to high-redshift counterparts.

No age or mass gradient with galactocentric distance was observed.

Results challenge the inward migration scenario for clump evolution.

Abstract

Giant, star-forming clumps are a common feature prevalent amongst high-redshift star-forming galaxies and play a critical role in shaping their chaotic morphologies and yet, their nature and role in galaxy evolution remains to be fully understood. A majority of the effort to study clumps has been focused at high redshifts, and local clump studies have often suffered from small sample sizes. In this work, we present an analysis of clump properties in the local universe, and for the first time, performed with a statistically significant sample. With the help of the citizen science-powered Galaxy Zoo: Hubble project, we select a sample of 92 $z<0.06$ clumpy galaxies in Sloan Digital Sky Survey Stripe 82 galaxies. Within this sample, we identify 543 clumps using a contrast-based image analysis algorithm and perform photometry as well as estimate their stellar population properties. The overall properties of our $z<0.06$ clump sample are comparable to the high-redshift clumps. However, contrary to the high-redshift studies, we find no evidence of a gradient in clump ages or masses as a function of their galactocentric distances. Our results challenge the inward migration scenario for clump evolution for the local universe, potentially suggesting a larger contribution of ex-situ clumps and/or longer clump migration timescales.