Tracing the evolutionary history of massive galaxies with globular clusters

Abstract

Massive, gravitationally bound star clusters, globular clusters (GCs) are among the oldest objects in the universe. Because they preferentially formed in the early universe, understanding their formation and evolution is challenging due to limited observational data. The James Webb Space Telescope (JWST) allows us to extend observations of GC populations to intermediate redshift; colour-magnitude diagrams (CMDs) and spatial distribution of GC populations can reveal the history of their host galaxies. By comparing CMDs of GC systems across epochs, we can further understand their evolution. These populations can also be used to probe the gravitational potential of massive galaxy clusters, which is dominated by the dark matter halo. This work focuses on the galaxy cluster RXJ 2129.5+0007 at a redshift of 0.234 (lookback time of 2.9 Gyr). We have conducted photometry utilizing three bands from the short wavelength channel of NIRCam (F115W, F150W, and F200W). We explore the CMD, radial and azimuthal distribution, and subpopulations of candidate GCs around the brightest cluster galaxy of RXJ 2129.