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Title: GLOBULAR CLUSTER POPULATIONS: FIRST RESULTS FROM S{sup 4}G EARLY-TYPE GALAXIES

Using 3.6 μm images of 97 early-type galaxies, we develop and verify methodology to measure globular cluster populations from the S{sup 4}G survey images. We find that (1) the ratio, T {sub N}, of the number of clusters, N {sub CL}, to parent galaxy stellar mass, M {sub *}, rises weakly with M {sub *} for early-type galaxies with M {sub *} > 10{sup 10} M {sub ☉} when we calculate galaxy masses using a universal stellar initial mass function (IMF) but that the dependence of T {sub N} on M {sub *} is removed entirely once we correct for the recently uncovered systematic variation of IMF with M {sub *}; and (2) for M {sub *} < 10{sup 10} M {sub ☉}, there is no trend between N {sub CL} and M {sub *}, the scatter in T {sub N} is significantly larger (approaching two orders of magnitude), and there is evidence to support a previous, independent suggestion of two families of galaxies. The behavior of N {sub CL} in the lower-mass systems is more difficult to measure because these systems are inherently cluster-poor, but our results may add to previous evidence that large variations in cluster formation andmore » destruction efficiencies are to be found among low-mass galaxies. The average fraction of stellar mass in clusters is ∼0.0014 for M {sub *} > 10{sup 10} M {sub ☉} and can be as large as ∼0.02 for less massive galaxies. These are the first results from the S{sup 4}G sample of galaxies and will be enhanced by the sample of early-type galaxies now being added to S{sup 4}G and complemented by the study of later-type galaxies within S{sup 4}G.« less
Authors:
 [1] ;  [2] ; ;  [3] ; ; ; ;  [4] ;  [5] ; ;  [6] ; ;  [7] ;  [8] ;  [9] ;  [10] ;  [11]
  1. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  2. Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Avenida Ejército 441, Santiago (Chile)
  3. Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France)
  4. Astronomy Division, Department of Physics, P.O. Box 3000, FI-90014 University of Oulu (Finland)
  5. IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)
  6. Instituto de Astrofísica de Canarias, Vía Lácteas, E-38205 La Laguna (Spain)
  7. European Southern Observatory, Casilla 19001, Santiago 19 (Chile)
  8. MMT Observatory, P.O. Box 210065, Tucson, AZ 85721 (United States)
  9. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
  10. Leiden Observatory, University of Leiden, Niels Bohrweg 4, NL-2333 Leiden (Netherlands)
  11. National Radio Astronomy Observatory/NAASC, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
Publication Date:
OSTI Identifier:
22364364
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; EFFICIENCY; GALACTIC EVOLUTION; GALAXIES; GALAXY CLUSTERS; IMAGES; MASS; STAR CLUSTERS; STAR EVOLUTION