Cosmic Collisions I: Optical Morphologies for MIRI-selected galaxies from the PRIMER survey

Abstract

We present the first results of visual morphology classifications from the Cosmic Collisions project, comprising 14,657 galaxies from the JWST Public Release IMaging for Extragalactic Research (PRIMER) survey. The sample consists of galaxies detected with MIRI F770W and spans the epoch of peak cosmic star formation (1<z<3). We produce rest-frame optical and observed-frame mid-IR images and enlisted citizen science volunteers through the Zooniverse platform to classify galaxy morphology, surface features, and interactions. The project accumulated 304,524 classifications from more than 4,700 volunteers. We find that mid-IR selected galaxies have significantly different morphologies relative to optical and near-IR selected galaxies, favoring dust-rich disk galaxies at z<2 and compact systems at z>2. This inverts findings from optical selection, which shows galaxies becoming more bulge-dominated and elliptical over cosmic time. In addition, we identify a population of galaxies with disk-like optical morphologies and luminous mid-IR point-source cores that may represent obscured AGN candidates, offering a promising path to identify AGNs based on imaging alone. Comparison with visual classifications from HST imaging demonstrates the impact of JWST's improved sensitivity and resolution on the identification of galaxy structure and interactions, with systems previously identified by HST as compact, smooth, or featureless showing significant extended and internal structure in JWST. These results provide a foundation for future investigations into the connection between morphology, dust structure, star formation, and AGN activity.

16 pages (19 w/ bibliography) 13 figures, 1 table. CSV of table 1 available on request (uploaded in future version)