New Insight into the stellar mass function of Galactic globular clusters
  We present the results of the analysis of deep photometric data of 32
Galactic globular clusters. We analysed 69 parallel field images observed with
the Wide Field Channel of the Advanced Camera for Surveys of the Hubble Space
Telescope which complemented the already available photometry from the globular
cluster treasury project covering the central regions of these clusters. This
unprecedented data set has been used to calculate the relative fraction of
stars at different masses (i.e. the present-day mass function) in these
clusters by comparing the observed distribution of stars along the cluster main
sequence and across the analysed field of view with the prediction of multimass
dynamical models. For a subsample of 31 clusters, we were able to obtain also
the half-mass radii, mass-to-light ratios and the mass fraction of dark
remnants using available radial velocity information. We found that the
majority of globular clusters have single power law mass functions $F(m)
\propto m^\alpha$ with slopes $\alpha>-1$ in the mass range
$0.2<m/\text{M}_{\odot}<0.8$. By exploring the correlations between the
structural/dynamical and orbital parameters, we confirm the tight
anticorrelation between the mass function slopes and the half-mass relaxation
times already reported in previous works, and possible second-order dependence
on the cluster metallicity. This might indicate the relative importance of both
initial conditions and evolutionary effects on the present-day shape of the
mass function.
