  The theory of homogeneously driven granular gases of hard particles predicts
that the stationary state is characterized by a velocity distribution function
with overpopulated high-energy tails as compared to the exponential decay valid
for molecular gases. While this fundamental theoretical result was confirmed by
numerous numerical simulations, an experimental confirmation is still missing.
Using self-rotating active granular particles, we find a power-law decay of the
velocity distribution whose exponent agrees well with the theoretic prediction.
