The Spatial Distribution of Intracluster Globular Clusters in the Fornax Cluster

Abstract We investigate the spatial distribution of the intracluster globular clusters (ICGCs) detected in the core of the Fornax galaxy cluster. By separately modeling different components of the observed population of globular clusters (GCs), we confirm the existence of an abundant ICGC overdensity with a geometrically complex, elongated morphology roughly centered on the cluster dominant galaxy NGC 1399 and stretching along the E–W direction. We identify several areas in the ICGC distribution that deviate from a simple elliptical model and feature large density enhancements. These regions are characterized based on their statistical significance, GCs excess number, position, size, and location relative to the galaxies in their surroundings. The relations between the spatial distribution and features of the ICGCs structures, mostly populated by blue GCs, and properties of the intracluster light and dwarf galaxies detected in the core of the Fornax cluster, are described and discussed. The line-of-sight velocity distribution of spectroscopically confirmed GCs within the ICGC structures is compatible with the systemic velocities of nearby bright galaxies in the Fornax cluster, suggesting that the ICGC population is at least partially composed of GCs stripped from their hosts. We argue that the findings here presented suggest that, on subcluster scales, different mechanisms contribute to the growth of the ICGC. The western region of Fornax is likely associated with old merging events that predate the assembly of the Fornax cluster. The eastern side instead points to a mix of tidal disruption of dwarf galaxies and stripping from the GCs system of massive hosts, more typical of relaxed, high-density cluster environments.