We have obtained two-dimensional velocity fields of the dwarf spiral galaxy NGC 2976 in H \alpha and CO .
The high spatial ( \sim 75 pc ) and spectral ( 13 km s ^ { -1 } and 2 km s ^ { -1 } , respectively ) resolution of these observations , along with our multicolor optical and near-infrared imaging , allow us to measure the shape of the density profile of the dark matter halo with good precision .
We find that the total ( baryonic plus dark matter ) mass distribution of NGC 2976 follows a \rho _ { \mbox { { \tiny TOT } } } \propto r ^ { -0.27 \pm 0.09 } power law out to a radius of 1.8 kpc , assuming that the observed radial motions provide no support .
The density profile attributed to the dark halo is even shallower , consistent with a nearly constant density of dark matter over the entire observed region .
A maximal disk fit yields an upper limit to the K-band stellar mass-to-light ratio ( M _ { * } / L _ { K } ) of 0.09 ^ { +0.15 } _ { -0.08 } \mbox { $M _ { \odot } / L _ { \odot K } $ } ( including systematic uncertainties ) , with the caveat that for \mbox { $M _ { * } / L _ { K } $ } > 0.19 \mbox { $M _ { \odot } / L _ { \odot K } $ } the dark matter density increases with radius , which is unphysical .
Assuming 0.10 \mbox { $M _ { \odot } / L _ { \odot K } $ } \lesssim \mbox { $M _ { * } / L _ { K } $ } \leq 0.19 \mbox { $% M _ { \odot } / L _ { \odot K } $ } , the dark matter density profile lies between \rho _ { \mbox { { \tiny DM } } } \propto r ^ { -0.17 } and \rho _ { \mbox { { \tiny DM } } } \propto r ^ { -0.01 } .
Therefore , independent of any assumptions about the stellar disk or the functional form of the density profile , NGC 2976 does not contain a cuspy dark matter halo .
We also investigate some of the systematic effects that can hamper rotation curve studies , and show that 1 ) longslit rotation curves are far more vulnerable to systematic errors than two-dimensional velocity fields , 2 ) NGC 2976 contains radial motions that are as large as 90 % of the rotational velocities at small radii , and 3 ) the H \alpha and CO velocity fields of NGC 2976 agree within their uncertainties , with a typical scatter between the two velocities of 5.3 km s ^ { -1 } at any position in the galaxy .