  We study how the Rashba spin-orbit interaction influences unconventional
superconductivity in a two dimensional electron gas partially spin-polarized by
a magnetic field. Somewhat surprisingly, we find that for all field
orientations, only the larger Fermi surface is superconducting. When the
magnetic field is oriented out-of-plane the system realizes a topological
$p+ip$ pairing state. When the field is rotated in-plane the order parameter
develops nodes along the field direction and finite center-of-mass-momentum
pairing is realized. We demonstrate that the pairing symmetry of the system can
be easily probed experimentally due to the dependence of various thermodynamic
quantities on the magnetic field geometry, and calculate the electronic
specific heat as an example.
