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Wide-Field Hubble Space Telescope Observations of the Globular Cluster System in NGC 1399*We present a comprehensive high spatial resolution imaging study of globular clusters (GCs) in NGC 1399, thecentral giant elliptical cD galaxy in the Fornax galaxy cluster, conducted with the Advanced Camera for Surveys(ACS) aboard theHubble Space Telescope(HST).Using a novel technique to construct drizzled point-spreadfunction libraries for HSTACS data, we accurately determine the fidelity of GC structural parameter measurementsfrom detailed artificial star cluster experiments and show the superior robustness of the GC half-light radius,rh,compared with other GC structural parameters, such as King core and tidal radius. The measurement ofrhfor themajor fraction of the NGC 1399 GC system reveals a trend of increasingrhversus galactocentric distance,Rgal,out to about 10 kpc and a flat relation beyond. This trend is very similar for blue and red GCs, which are found tohave a mean size ratio ofrh,redrh,blue0.820.11 at all galactocentric radii from the core regions of the galaxyout to40 kpc. This suggests that the size difference between blue and red GCs is due to internal mechanismsrelated to the evolution of their constituent stellar populations. Modeling the mass density profile of NGC 1399shows that additional external dynamical mechanisms are required to limit the GC size in the galaxy halo regionstorh2 pc. We suggest that this may be realized by an exotic GC orbit distribution function, an extended darkmatter halo, andor tidal stress induced by the increased stochasticity in the dwarf halo substructure at largergalactocentric distances. We compare our results with the GCrhdistribution functions in various galaxies and findthat the fraction of extended GCs withrh5 pc is systematically larger in late-type galaxies compared with GCsystems in early-type galaxies. This is likely due to the dynamically more violent evolution of early-type galaxies.We match our GCrhmeasurements with radial velocity data from the literature and split the resulting sample at themedianrhvalue into compact and extended GCs. We find that compact GCs show a significantly smaller line-of-sight velocity dispersion,cmp22525 km s1, than their extended counterparts,ext31721 km s1.Considering the weaker statistical correlation in the GCrhcolor and the GCrhRgalrelations, the more significantGC sizedynamics relation appears to be astrophysically more relevant and hints at the dominant influence of theGC orbit distribution function on the evolution of GC structural parameters.
Document ID
20150008996
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Puzia, Thomas H.
(Universidad Catolica de Chile Santiago, Chile)
Paolillo, Maurizio
(Naples Univ. Italy)
Goudfrooij, Paul
(Space Telescope Science Inst. Baltimore, MD, United States)
Maccarone, Thomas J.
(Texas Tech Univ. Lubbock, TX, United States)
Fabbiano, Giuseppina
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Angelini, Lorella
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
May 28, 2015
Publication Date
April 17, 2014
Publication Information
Publication: The Astrophysical Journal
Publisher: The Astrophysical Journal
Volume: 786
Issue: 2
Subject Category
Astrophysics
Astronomy
Report/Patent Number
GSFC-E-DAA-TN21839
Funding Number(s)
CONTRACT_GRANT: NNX09AF08G
CONTRACT_GRANT: NAS5-26555
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Hubble
Space
Wide-Field
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