Star formation in clumpy, interacting galaxies

Abstract

Galaxy mergers are one of the most important processes in the universe - they are a method of galaxy growth and mass assembly, and also the cause of internal dynamic changes in galaxies including star formation and quenching. In this thesis we examine two populations of interacting galaxies with data from the James Webb and Hubble space telescopes, and two equivalent populations of isolated galaxies, in order to examine the star formation trends, but also the presence of star-forming clumps of material in galactic disks. The analysis on star formation is based on a combination of the results from broadband spectral energy distribution (SED) fitting of imaging data, and Hα emission line maps from 2D slitless grism spectroscopy. We present the development and applications of a ‘clump’ detection algorithm, and examine the clumpiness of all galaxies in both samples. We find that within a narrow mass range (between 109 − 1010M⊙) that interacting galaxies are higher in both star formation rate and number of clumps, supporting common theories that mergers induce star formation, and that they are potentially tied to clump formation. Using emission line maps and the results of spectral energy distribution (SED) fitting, we investigate the clump contributions to galaxy star formation rate (SFR), comparing these results to the literature and use their behaviour to explain overall star formation and clump trends in mergers.