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

Using deep photometric data from WFC@INT and WFI@ESO2.2m 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

-\gamma

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 < \gamma < 4

and a group of low-mass clusters (

\le 10^5

M_sun), with steep profiles (

\gamma > 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.

Note:

17 pages, 14 figures, 2 tables; accepted for publication in MNRAS

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