The Dark Matter Distributions in Low-Mass Disk Galaxies. II. The Inner
  Density Profiles
  Dark matter-only simulations predict that dark matter halos have steep, cuspy
inner density profiles, while observations of dwarf galaxies find a range of
inner slopes that are often much shallower. There is debate whether this
discrepancy can be explained by baryonic feedback or if it may require modified
dark matter models. In Paper 1 of this series, we obtained high-resolution
integral field H$\alpha$ observations for 26 dwarf galaxies with
$M_*=10^{8.1}-10^{9.7}\textrm{M}_\odot$. We derived rotation curves from our
observations, which we use here to construct mass models. We model the total
mass distribution as the sum of a generalized Navarro-Frenk-White (NFW) dark
matter halo and the stellar and gaseous components. Our analysis of the slope
of the dark matter density profile focuses on the inner 300-800 pc, chosen
based on the resolution of our data and the region resolved by modern
hydrodynamical simulations. The inner slope measured using ionized and
molecular gas tracers is consistent, and it is additionally robust to the
choice of stellar mass-to-light ratio. We find a range of dark matter profiles,
including both cored and cuspy slopes, with an average of $\rho_{\rm DM}\sim
r^{-0.74\pm 0.07}$, shallower than the NFW profile, but steeper than those
typically observed for lower-mass galaxies with $M_*\sim
10^{7.5}\textrm{M}_\odot$. Simulations that reproduce the observed slopes in
those lower-mass galaxies also produce slopes that are too shallow for galaxies
in our mass range. We therefore conclude that supernova feedback models do not
yet provide a fully satisfactory explanation for the observed trend in dark
matter slopes.
