SED Fitting of Globular Cluster Population in Abell 2744 at an Intermediate Redshift

Abstract

Globular clusters (GCs) are ancient, compact stellar systems that serve as laboratories for stellar evolution and as fossil records of galaxy assembly, with their ages, metallicites, and spatial distributions constraining star-formation histories and the evolution of halos. This thesis presents SED fitting analysis of unresolved GC candidates in Abell 2744 at z = 0.308 using JWST/NIRCam images in eight filters (F070W-F444W). After PSF-fitting photometry and strict data selection, we retain 67 candidates with detections in all bands. Model magnitudes are generated by convolving E-MILES simple stellar population spectra and fit dirctly to the observed photometry. Age, metallicity, and mass of the GC candidates are estimated in parallel via $\chi^2$ minimization and MCMC. Both approaches deliver mutually consistent results. The inferred stellar masses of the candidates are mostly around $10^7M_{\odot}$, ages around $\sim$6 Gyr and $\sim$10 Gyr, and metallicities mostly between $-0.66\lesssim\text{[M/H]}\lesssim0.06$. We also explore the limitation of SED fitting of this data such as age-mass degeneracy and LWC dimming.