The low dark matter content of the lenticular galaxy NGC 3998
  We observed the lenticular galaxy NGC 3998 with the Mitchell Integral-Field
Spectrograph and extracted line-of-sight velocity distributions out to 3
half-light radii. We constructed collisionless orbit models in order to
constrain NGC 3998's dark and visible structure, using kinematics from both the
Mitchell and SAURON instruments. We find NGC 3998 to be almost axisymmetric,
seen nearly face on with a flattened intrinsic shape - i.e., a face-on
fast-rotator. We find an I-band mass-to-light ratio of $4.7_{-0.45}^{+0.32}$ in
good agreement with previous spectral fitting results for this galaxy. Our
best-fit orbit model shows a both a bulge and a disc component, with a
non-negligible counter-rotating component also evident. We find that relatively
little dark matter is needed to model this galaxy, with an inferred dark mass
fraction of just $(7.1^{+8.1}_{-7.1})\%$ within one half-light radius.
