Journal Article

Outer density profiles of 19 Galactic globular clusters from deep and wide-field imaging

Julio A. Carballo-Bello, Mark Gieles, Antonio Sollima, Sergey Koposov, David Martínez-Delgado and Jorge Peñarrubia

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 419, issue 1, pages 14-28
Published in print January 2012 | ISSN: 0035-8711
Published online December 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19663.x
Outer density profiles of 19 Galactic globular clusters from deep and wide-field imaging

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Using deep photometric data from Wide Field Camera at the Isaac Newton Telescope and Wide Field Imager at the ESO 2.2-m telescope we measure the outer number density profiles of 19 stellar clusters located in the inner region of the Milky Way halo (within a Galactocentric distance range of 10–30 kpc) in order to assess the impact of internal and external dynamical processes on the spatial distribution of stars. Adopting power-law fitting templates, with index −γ in the outer region, we find that the clusters in our sample can be divided in two groups: a group of massive clusters (≥105 M) that has relatively flat profiles with 2.5 < γ < 4, and a group of low-mass clusters (≤105 M), with steep profiles (γ > 4) and clear signatures of interaction with the Galactic tidal field. We refer to these two groups as ‘tidally unaffected’ and ‘tidally affected’, respectively. Our results also show a clear trend between the slope of the outer parts and the half-mass density of these systems, which suggests that the outer density profiles may retain key information on the dominant processes driving the dynamical evolution of globular clusters.

Keywords: methods: observational; techniques: photometric; stars: Population II; globular clusters: general

Journal Article.  9030 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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