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

Using deep photometric data from WFC@INT and [email protected] 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 ($\ge 10^5$ M_sun) that has relatively flat profiles with $2.5 < γ< 4$ and a group of low-mass clusters ($\le 10^5$ M_sun), 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.

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