We have developed spherically symmetric dynamical models of dwarf spheroidal galaxies using Schwarzschild ’ s orbit superposition method .
This type of modelling yields constraints both on the total mass distribution ( e.g .
enclosed mass and scale radius ) as well as on the orbital structure of the system ( e.g .
velocity anisotropy ) .
This method is thus less prone to biases introduced by assumptions in comparison to the more commonly used Jeans modelling , and it allows us to derive the dark matter content in a robust way .
Here we present our results for the Sculptor dwarf spheroidal galaxy , after testing our methods on mock data sets .
We fit both the second and fourth velocity moment profile to break the mass-anisotropy degeneracy .
For an NFW dark matter halo profile , we find that the mass of Sculptor within 1 kpc is \text { M } _ { 1 \text { kpc } } = ( 1.03 \pm 0.07 ) \times 10 ^ { 8 } \text { M } _ { \odot } , and that its velocity anisotropy profile is tangentially biased and nearly constant with radius .
The preferred concentration ( c \sim 15 ) is low for its dark matter mass but consistent within the scatter found in N-body cosmological simulations .
When we let the value of the central logarithmic slope \alpha vary , we find that the best-fit model has \alpha = 0 , although an NFW cusp or shallower is consistent at 1 \sigma confidence level .
On the other hand , very cuspy density profiles with logarithmic central slopes \alpha < -1.5 are strongly disfavoured for Sculptor .