  Fluctuating hydrodynamics is used to describe the total energy fluctuations
of a freely evolving gas of inelastic hard spheres near the threshold of the
clustering instability. They are shown to be governed by vorticity fluctuations
only, that also lead to a renormalization of the average total energy. The
theory predicts a power-law divergent behavior of the scaled second moment of
the fluctuations, and a scaling property of their probability distribution,
both in agreement with simulations results. A more quantitative comparison
between theory and simulation for the critical amplitudes and the form of the
scaling function is also carried out.
