A class of spherical, truncated, anisotropic models for application to
  globular clusters
  Recently, a class of non-truncated radially-anisotropic models (the so-called
$f^{(\nu)}$-models), originally constructed in the context of violent
relaxation and modeling of elliptical galaxies, has been found to possess
interesting qualities in relation to observed and simulated globular clusters.
In view of new applications to globular clusters, we improve this class of
models along two directions. To make them more suitable for the description of
small stellar systems hosted by galaxies, we introduce a 'tidal' truncation (by
means of a procedure that guarantees full continuity of the distribution
function). The new $f_T^{(\nu)}$-models are shown to provide a better fit to
the observed photometric and spectroscopic profiles for a sample of 13 globular
clusters studied earlier by means of non-truncated models; interestingly, the
best-fit models also perform better with respect to the radial-orbit
instability. Then we design a flexible but simple two-component family of
truncated models, to study the separate issues of mass segregation and of
multiple populations. We do not aim at a fully realistic description of
globular clusters, to compete with the description currently obtained by means
of dedicated simulations. The goal here is to try to identify the simplest
models, that is, those with the smallest number of free parameters, but still
able to provide a reasonable description for clusters that are evidently beyond
the reach of one-component models: with this tool we aim at identifying the key
factors that characterize mass segregation or the presence of multiple
populations. To reduce the relevant parameter space, we formulate a few
physical arguments (based on recent observations and simulations). A first
application to two well-studied globular clusters is briefly described and
discussed.
