  We investigate numerically the applicability of dynamic facilitation (DF)
theory for glass-forming binary hard disk systems where supercompression is
controlled by pressure. By using novel efficient algorithms for hard disks, we
are able to generate equilibrium supercompressed states in an additive
non-equimolar binary mixture, where micro-crystallization and size segregation
do not emerge at high average packing fractions. Above an onset pressure where
collective heterogeneous relaxation sets in, we find that relaxation times are
well described by a "parabolic law" with pressure. We identify excitations, or
soft-spots, that give rise to structural relaxation, and find that they are
spatially localized, their average concentration decays exponentially with
pressure, and their associated energy scale is logarithmic in the excitation
size. These observations are consistent with the predictions of DF generalized
to systems controlled by pressure rather than temperature.
