  In this article we study the conditions under which holographic metallic
states display Friedel oscillations. We focus on systems where the bulk charge
density is not hidden behind a black hole horizon. Understanding holographic
Friedel oscillations gives a clean way to characterize the boundary system,
complementary to probe fermion calculations. We find that fermions in a "hard
wall" AdS geometry unambiguously display Friedel oscillations. However, similar
oscillations are washed out for electron stars, suggesting a smeared continuum
of Fermi surfaces.
