The globular cluster population in the core of the Coma Cluster of Galaxies

Abstract

In this study we attempt to discover, using data taken by Bernstein et al. (1995, Bea95), whether there exists a population of intracluster globular clusters (IGC) within the core of the Coma Cluster of Galaxies. Models are created in an effort to try to match the distribution of unresolved objects in the Bea95 catalogue within the globular cluster magnitude range at the distance of Coma, and tested using a two-dimensional, two-sample Kolmogorov-Smirnov test for compatibility. The best-fitting model was found to be composed of an 81% background component, an 18% NGC 4874 globular cluster component with a King-profile core radius of approximately 3.7' and a 1% IGC component with a King-profile core radius of approximately 18'. Since the Bea95 background estimate from blank fields of similar galactic latitudes as the Coma field indicates that the background count in the Coma field accounts for only 74% of the unresolved objects in this range, it is possible that the remaining 7% of the objects found to belong to the background actually belongs to the similarly flat IGC component, raising its total count to 8% of the total number of objects. However, the 3[sigma] uncertainty in the Bea95 background estimate leaves this possibility debatable. Tests of the effectiveness of the method and the similarity of the core radius values to those of X-ray distribution measurements seem to confirm (within the 1[sigma] uncertainty) that this model describes the true distribution correctly. However, model result and background count uncertainties are sufficient to prevent making a firm claim on the existence of IGCs. Better data is required to make this method truly viable in determining their presence.