  I report recent results of numerical simulations designed to study the inner
structure of Cold Dark Matter (CDM) halos. This work confirms the proposal of
Navarro, Frenk & White (NFW) that the shape of LambdaCDM halo mass profiles
differs strongly from a power law and is approximately independent of mass. The
logarithmic slope of the spherically-averaged density profile, as measured by
beta=-dln(rho)/dlnr, decreases monotonically towards the center, becomes
shallower than isothermal (beta<2) inside a characteristic radius, r_{-2}, and
shows no evidence for convergence to a well-defined asymptotic value (beta_0)
at the center. The dark mass contained within the innermost radius resolved by
the simulations places strong constraints on beta_0; cusps as steep as r^{-1.5}
are clearly ruled out in our highest resolution simulations. A profile where
the radial dependence of the slope is a simple power law, beta(r)\propto
r^{\alpha}, approximates the structure of halos better than the NFW profile and
so may minimize errors when extrapolating our results inward to radii not yet
reliably probed by numerical simulations. We compare the spherically-averaged
circular velocity (V_c) profiles to the rotation curves of low surface
brightness (LSB) galaxies in the samples of de Blok et al and Swaters et al.
The V_c profiles of simulated CDM halos are generally consistent with the
rotation curves of LSB galaxies, but there are also some clearly discrepant
cases. This disagreement has been interpreted as excluding the presence of
cusps, but it may also just reflect the difference between circular velocity
and rotation speed likely to arise in gaseous disks embedded within realistic
triaxial halos.
