We introduce a novel implementation of orbit-based ( or Schwarzschild ) modeling that allows dark matter density profiles to be calculated non-parametrically in nearby galaxies .
Our models require no assumptions to be made about velocity anisotropy or the dark matter profile .
The technique can be applied to any dispersion-supported stellar system , and we demonstrate its use by studying the Local Group dwarf spheroidal ( dSph ) galaxy Draco .
We use existing kinematic data at larger radii and also present 12 new radial velocities within the central 13 pc obtained with the VIRUS-W integral field spectrograph on the 2.7m telescope at McDonald Observatory .
Our non-parametric Schwarzschild models find strong evidence that the dark matter profile in Draco is cuspy for 20 \leq r \leq 700 pc .
The profile for r \geq 20 pc is well-fit by a power law with slope \alpha = -1.0 \pm 0.2 , consistent with predictions from Cold Dark Matter ( CDM ) simulations .
Our models confirm that , despite its low baryon content relative to other dSphs , Draco lives in a massive halo .