JWST Photometry of Globular Clusters in Abell 2744. II: luminosity and color distributions

Abstract

Deep JWST imaging of the giant galaxy cluster Abell 2744, at redshift $z=0.308$, is used to explore the features of its rich population of globular clusters (GCs), building on our initial survey of the system (Harris & Reina-Campos 2023). We use the photometry of more than $10,000$ GCs over a three-magnitude range to construct the GC luminosity function (GCLF) and color distribution (CDF). These results now specifically account for photometric incompleteness as a function of location relative to the five giant galaxies that dominate the gravitational potential of A2744. The total GC population in A2744 is estimated at $N_{\rm GC} \geq 1.1 \times 10^5$, consistent with its high total mass. We also directly compare the observed distributions with theoretical predictions for GC populations drawn from the recent EMP-Pathfinder simulations (Reina-Campos et al. 2022), viewed at the same 3.5 Gyr lookback time as the cluster. The simulations match the observations well, with the only notable disagreement being that the simulations predict larger numbers of GCs at high metallicity formed after $z\simeq2$ than are seen in the data.