Isolated Ellipticals and Their Globular Cluster Systems III. NGC 2271, NGC
Astronomy & Astrophysics manuscript no. salinas+15_arxiv c ESO 2018 October 5, 2018 Isolated ellipticals and their globular cluster systems III. NGC 2271, NGC 2865, NGC 3962, NGC 4240 and IC 4889 ⋆ R. Salinas1, 2, A.Alabi3, 4, T. Richtler5, and R. R. Lane5 1 Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Piikkiö, Finland 2 Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA 3 Tuorla Observatory, University of Turku, Väisäläntie 20, FI-21500 Piikkiö, Finland 4 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122, Australia 5 Departamento de Astronomía, Universidad de Concepción, Concepción, Chile Accepted 21 Feb 2015 ABSTRACT As tracers of star formation, galaxy assembly and mass distribution, globular clusters have provided important clues to our under- standing of early-type galaxies. But their study has been mostly constrained to galaxy groups and clusters where early-type galaxies dominate, leaving the properties of the globular cluster systems (GCSs) of isolated ellipticals as a mostly uncharted territory. We present Gemini-South/GMOS g′i′ observations of five isolated elliptical galaxies: NGC 3962, NGC 2865, IC 4889, NGC 2271 and NGC 4240. Photometry of their GCSs reveals clear color bimodality in three of them, remaining inconclusive for the other two. All the studied GCSs are rather poor with a mean specific frequency S N 1.5, independently of the parent galaxy luminosity. Considering also previous work, it is clear that bimodality and especially the presence∼ of a significant, even dominant, population of blue clusters occurs at even the most isolated systems, casting doubts on a possible accreted origin of metal-poor clusters as suggested by some models.
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