Schwarzschild dynamical model of the Fornax dwarf spheroidal galaxy
  We present a full dynamical model of the Fornax dwarf spheroidal galaxy
obtained with the spherically symmetric Schwarzschild orbit superposition
method applied to the largest kinematic data set presently available. We
modelled the total mass content of the dwarf with the mass-to-light ratio
$\Upsilon$ varying with radius and found that Fornax is with high probability
embedded in a massive and extended dark matter halo. We estimated the total
mass contained within 1$\,$kpc to be $M(<1\,$kpc$)=1.25^{+0.06}_{-0.13} \times
10^8\,$M$_{\odot}$. The data are consistent with the constant mass-to-light
ratio, i.e. the mass-follows-light model, only at 3$\sigma$ level, but still
require a high value of $\Upsilon \approx 11.2\,$M$_{\odot}/$L$_{\odot}$. Our
results are in general agreement with previous estimates of the dynamical mass
profile of Fornax. As the Schwarzschild method does not require any assumptions
on the orbital anisotropy of the stars, we obtained a profile of the anisotropy
parameter $\beta$ as an output of our modelling. The derived anisotropy is
close to zero in the centre of the galaxy and decreases with radius, but
remains consistent with isotropic orbits at all radii at 1$\sigma$ confidence
level.
