High-Resolution Dark Matter Density Profiles of Things Dwarf Galaxies: Correcting for Noncircular Motions

We present a new method to remove the impact of random and small-scale noncircular motions from Hi velocity fields in (dwarf) galaxies in order to better constrain the dark matter properties for these objects. This method extracts the circularly rotating velocity components from the Hi data cube and condenses them into a so-called bulk velocity field. We derive high-resolution ( ∼ 0.2 kpc) rotation curves of IC 2574 and NGC 2366 based on bulk velocity fields derived from The HI Nearby Galaxy Survey (THINGS) obtained at the VLA. We compare the bulk velocity field rotation curves with those derived from the traditional intensity-weighted mean velocity fields and find significant differences. The bulk velocity field rotation curves are significantly less affected by non-circular motions and constrain the dark matter distribution in our galaxies, allowing us to address the discrepancy between the inferred and predicted dark matter distribution in galaxies (the “cusp/core ” problem). Spitzer Infrared Nearby Galaxies Survey (SINGS) 3.6 µm data, which are largely unaffected by dust in these systems, as well as ancillary optical information, are used to separate the contribution of the baryons from the total matter content. Using stellar population synthesis models, assuming various sets of metallicity and star formation histories, we compute stellar mass-to-light 1