  We image equilibrium and non-equilibrium transport through a two-dimensional
electronic cavity using scanning gate microscopy (SGM). Injecting electrons
into the cavity through a quantum point contact close to equilibrium, we
raster-scan a weakly invasive tip above the cavity regions and measure the
modulated conductance through the cavity. Varying the electron injection energy
between $\pm$ 2 meV, we observe that conductance minima turn into maxima beyond
the energy threshold of $\pm$ 0.6 meV. This observation bears similarity to
previous measurements by Jura et al. [Jura et al., Phys. Rev. B 82, 155328
(2010)] who used a strongly invasive tip potential to study electron injection
into an open two-dimensional electron gas. This resemblance suggests a similar
microscopic origin based on electron-electron interactions.
