The central dark matter distribution of NGC 2976
  We study the mass distribution in the late-type dwarf galaxy NGC 2976 through
stellar kinematics obtained with the VIRUS-P integral-field spectrograph and
anisotropic Jeans models as a test of cosmological simulations and baryonic
processes that putatively alter small-scale structure. Previous measurements of
the H-alpha emission-line kinematics have determined that the dark matter halo
of NGC 2976 is most consistent with a cored density profile. We find that the
stellar kinematics are best fit with a cuspy halo. Cored dark matter halo fits
are only consistent with the stellar kinematics if the stellar mass-to-light
ratio is significantly larger than that derived from stellar population
synthesis, while the best-fitting cuspy model has no such conflict. The
inferred mass distribution from a harmonic decomposition of the gaseous
kinematics is inconsistent with that of the stellar kinematics. This difference
is likely due to the gas disk not meeting the assumptions that underlie the
analysis such as no pressure support, a constant kinematic axis, and planar
orbits. By relaxing some of these assumptions, in particular the form of the
kinematic axis with radius, the gas-derived solution can be made consistent
with the stellar kinematic models. A strong kinematic twist in the gas of NGC
2976's center suggests caution, and we advance the mass model based on the
stellar kinematics as more reliable. The analysis of this first galaxy shows
promising evidence that dark matter halos in late-type dwarfs may in fact be
more consistent with cuspy dark matter distributions than earlier work has
claimed.
