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G2C2, III : structural parameters for Galactic globular clusters in SDSS passbands

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Abstract
We use our Galactic Globular Cluster Catalog (G2C2) photometry for 111 Galactic globular clusters (GCs) in g and z, as well as r and i photometry for a subset of 60 GCs and u photometry for 22 GCs, to determine the structural parameters assuming King models. In general, the resulting core radii are in good comparison with the current literature values. However, our half-light radii are slightly lower than the literature. The concentrations (and therefore also the tidal radii) are poorly constrained mostly because of the limited radial extent of our imaging. Therefore, we extensively discuss the effects of a limited field of view on the derived parameters using mosaicked Sloan Digital Sky Survey data, which do not suffer from this restriction. We also illustrate how red giant branch (RGB) stars in cluster cores can stochastically induce artificial peaks in the surface brightness profiles. The issues related to these bright stars are scrutinized based on both our photometry and simulated clusters. We also examine colour gradients and find that the strongest central colour gradients are caused by central RGB stars and thus not representative for the cluster light or colour distribution. We recover the known relation between the half-light radius and the Galactocentric distance in the g band, but find a lower slope for redder filters. We did not find a correlation between the scatter on this relation and other cluster properties. We find tentative evidence for a correlation between the half-light radii and the [Fe/H], with metal-poor GCs being larger than metal-rich GCs. However, we conclude that this trend is caused by the position of the clusters in the Galaxy, with metal-rich clusters being more centrally located.
Keywords
HORIZONTAL-BRANCH MORPHOLOGY, globular clusters: general, SURFACE-BRIGHTNESS PROFILES, CORE-COLLAPSE, LARGE-MAGELLANIC-CLOUD, DIGITAL SKY SURVEY, HALF-LIGHT RADII, BLUE STRAGGLER STARS, EARLY-TYPE GALAXIES, MASSIVE STAR-CLUSTERS, MILKY-WAY

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Citation

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Chicago
Vanderbeke, Joachim, Roberto De Propris, Sven De Rijcke, Maarten Baes, Michael J West, and John P Blakeslee. 2015. “G2C2, III : Structural Parameters for Galactic Globular Clusters in SDSS Passbands.” Monthly Notices of the Royal Astronomical Society 450 (3): 2692–2707.
APA
Vanderbeke, J., De Propris, R., De Rijcke, S., Baes, M., West, M. J., & Blakeslee, J. P. (2015). G2C2, III : structural parameters for Galactic globular clusters in SDSS passbands. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 450(3), 2692–2707.
Vancouver
1.
Vanderbeke J, De Propris R, De Rijcke S, Baes M, West MJ, Blakeslee JP. G2C2, III : structural parameters for Galactic globular clusters in SDSS passbands. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. 2015;450(3):2692–707.
MLA
Vanderbeke, Joachim et al. “G2C2, III : Structural Parameters for Galactic Globular Clusters in SDSS Passbands.” MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 450.3 (2015): 2692–2707. Print.
@article{7058595,
  abstract     = {We use our Galactic Globular Cluster Catalog (G2C2) photometry for 111 Galactic globular clusters (GCs) in g and z, as well as r and i photometry for a subset of 60 GCs and u photometry for 22 GCs, to determine the structural parameters assuming King models. In general, the resulting core radii are in good comparison with the current literature values. However, our half-light radii are slightly lower than the literature. The concentrations (and therefore also the tidal radii) are poorly constrained mostly because of the limited radial extent of our imaging. Therefore, we extensively discuss the effects of a limited field of view on the derived parameters using mosaicked Sloan Digital Sky Survey data, which do not suffer from this restriction. We also illustrate how red giant branch (RGB) stars in cluster cores can stochastically induce artificial peaks in the surface brightness profiles. The issues related to these bright stars are scrutinized based on both our photometry and simulated clusters. We also examine colour gradients and find that the strongest central colour gradients are caused by central RGB stars and thus not representative for the cluster light or colour distribution. We recover the known relation between the half-light radius and the Galactocentric distance in the g band, but find a lower slope for redder filters. We did not find a correlation between the scatter on this relation and other cluster properties. We find tentative evidence for a correlation between the half-light radii and the [Fe/H], with metal-poor GCs being larger than metal-rich GCs. However, we conclude that this trend is caused by the position of the clusters in the Galaxy, with metal-rich clusters being more centrally located.},
  author       = {Vanderbeke, Joachim and De Propris, Roberto and De Rijcke, Sven and Baes, Maarten and West, Michael J and Blakeslee, John P},
  issn         = {0035-8711},
  journal      = {MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY},
  language     = {eng},
  number       = {3},
  pages        = {2692--2707},
  title        = {G2C2, III : structural parameters for Galactic globular clusters in SDSS passbands},
  url          = {http://dx.doi.org/10.1093/mnras/stv850},
  volume       = {450},
  year         = {2015},
}

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