Webb, Jeremy J.Jeremy J.WebbSills, AlisonAlisonSillsHarris, William E.William E.HarrisGómez, MatíasMatíasGómezPaolillo, MaurizioMaurizioPaolilloWoodley, Kristin A.Kristin A.WoodleyPuzia, Thomas H.Thomas H.Puzia2020-07-132020-07-1320160035-8711http://hdl.handle.net/20.500.12386/26427We investigate the shallow increase in globular cluster half-light radii with projected galactocentric distance R<SUB>gc</SUB> observed in the giant galaxies M87, NGC 1399, and NGC 5128. To model the trend in each galaxy, we explore the effects of orbital anisotropy and tidally underfilling clusters. While a strong degeneracy exists between the two parameters, we use kinematic studies to help constrain the distance R<SUB>β</SUB> beyond which cluster orbits become anisotropic, as well as the distance R<SUB>fα</SUB> beyond which clusters are tidally underfilling. For M87 we find R<SUB>β</SUB> > 27 kpc and 20 < R<SUB>fα</SUB> < 40 kpc and for NGC 1399 R<SUB>β</SUB> > 13 kpc and 10 < R<SUB>fα</SUB> < 30 kpc. The connection of R<SUB>fα</SUB> with each galaxy's mass profile indicates the relationship between size and R<SUB>gc</SUB> may be imposed at formation, with only inner clusters being tidally affected. The best-fitting models suggest the dynamical histories of brightest cluster galaxies yield similar present-day distributions of cluster properties. For NGC 5128, the central giant in a small galaxy group, we find R<SUB>β</SUB> > 5 kpc and R<SUB>fα</SUB> > 30 kpc. While we cannot rule out a dependence on R<SUB>gc</SUB>, NGC 5128 is well fitted by a tidally filling cluster population with an isotropic distribution of orbits, suggesting it may have formed via an initial fast accretion phase. Perturbations from the surrounding environment may also affect a galaxy's orbital anisotropy profile, as outer clusters in M87 and NGC 1399 have primarily radial orbits while outer NGC 5128 clusters remain isotropic.STAMPAenArticle10.1093/mnras/stw11152-s2.0-84983082785000379832800077https://academic.oup.com/mnras/article/460/2/2129/26091012016MNRAS.460.2129WFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_6 Stars and stellar systems