  We present analytical expressions and numerical illustrations for the
ground-state density distribution of an ideal gas of spin-polarized fermions
moving in two dimensions and driven to rotate in a harmonic well of circular or
elliptical shape. We show that with suitable choices of the strength of the
Lorentz force for charged fermions, or of the rotational frequency for neutral
fermions, the density of states can be tuned as a function of the angular
momentum so as to display a prominent shell structure in the spatial density
profile of the gas. We also show how this feature of the density profile is
revealed in the static structure factor determining the elastic light
scattering spectrum of the gas.
