Structural parameters for globular clusters in NGC 5128 – III. ACS surface brightness profiles and model fits |
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| Authors: | Dean E McLaughlin Pauline Barmby William E Harris Duncan A Forbes Gretchen L H Harris |
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| Institution: | School of Physical and Geographical Sciences, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG;Department of Physics and Astronomy, University of Western Ontario, London, ON, Canada N6A 3K7;Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada L8S 4M1;Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122, Australia;Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada N2L 3G1 |
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| Abstract: | We present internal surface brightness profiles, based on Hubble Space Telescope /ACS imaging in the F 606 W bandpass, for 131 globular cluster (GC) candidates with luminosities L ? 104–3 × 106 L⊙ in the giant elliptical galaxy NGC 5128. Several structural models are fitted to the profile of each cluster and combined with mass-to-light ratios ( M / L values) from population-synthesis models, to derive a catalogue of fundamental structural and dynamical parameters parallel in form to the catalogues recently produced by McLaughlin & van der Marel and by Barmby et al. for GCs and massive young star clusters in Local Group galaxies. As part of this, we provide corrected and extended parameter estimates for another 18 clusters in NGC 5128, which we observed previously. We show that, like GCs in the Milky Way and some of its satellites, the majority of globulars in NGC 5128 are well fitted by isotropic Wilson models, which have intrinsically more distended envelope structures than the standard King lowered isothermal spheres. We use our models to predict internal velocity dispersions for every cluster in our sample. These predictions agree well in general with the observed dispersions in a small number of clusters for which spectroscopic data are available. In a subsequent paper, we use these results to investigate scaling relations for GCs in NGC 5128. |
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| Keywords: | globular clusters: general galaxies: star clusters |
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