A Gemini/GMOS study of the bright elliptical galaxy NGC 3613 and its globular cluster system

Abstract

We present the first photometric study ofthe globular cluster system (GCS) of the E galaxy NGC3613 (MV = −21.5, d ∼ 30.1Mpc), as well as the surfacephotometry of the host galaxy, based on Gemini/GMOS images. Beingconsidered the central galaxy of a group, NGC3613 inhabits a low-density environmentalthough its intrinsic brightness is similar to the expected one for galaxies in the centre ofclusters. The following characteristics are obtained for this GCS. The colour distribution isbimodal, with metal-poor globular clusters (GCs) getting slightly bluer with increasing radius. Theradial and azimuthal projected distributions show that metal-rich GCs are more concentratedtowards the host galaxy and trace its light distribution very precisely, while metal-poor GCspresent a more extended and uniform distribution. The GC luminosity function helps validate theadopted distance. The estimated total GC population of Ntot = 2075 ± 130 leads to a specific frequency SN = 5.2 ± 0.7, a value within the expected range for with host galaxies of similar luminosity. Thesurface photometry of NGC3613 reveals a three-component profile and anoticeable substructure. Finally, a small sample of ultracompact dwarf candidates are identified in the surroundings of thehost galaxy.