The S-PLUS Fornax Project (S+FP): Mapping Globular Clusters Systems within 5 Virial Radii around NGC 1399

Abstract

We present the largest sample (∼13,000 candidates, ∼3000 of which are bona fide candidates) of globular cluster (GCs) candidates reported in the Fornax cluster so far. The survey is centered on the NGC 1399 galaxy, extending out to 5 virial radii ( R _vir ) of the cluster. We carried out a photometric study using images observed in the 12-band system of the Southern Photometric Local Universe Survey (S-PLUS), corresponding to 106 pointings, covering a sky area of ∼208 square degrees. Studying the properties of spectroscopically confirmed GCs, we have designed a method to select GC candidates using structural and photometric parameters. We found evidence of color bimodality in two broadband colors, namely ( g − i ) _0 and ( g − z ) _0 , while, in the narrow bands, we did not find strong statistical evidence to confirm bimodality in any color. We analyzed the GCs luminosity functions (GCLF) in the 12 bands of S-PLUS, and we can highlight two points: (a) due to the relatively shallow depth of S-PLUS, it is only possible to observe the bright end of the GCLF and, (b) at that level, in all of the bands, it can be considered to be the log-normal distribution typical for GC systems. With the spatial coverage reached in this study, we are able, for the first time, to explore the large-scale distribution of GCs within and around a galaxy cluster. In particular, we noted that the GCs might be clustered along substructures, which trace the current cluster buildup.

Keywords

• Globular star clusters
• Galaxy clusters
• Surveys
• Galaxy formation
• Galaxy evolution