Radiative shock waves are observed around astronomical objects in a
wide variety of environments, for example, they herald the birth of stars
and sometimes their death. Such shocks can also be created in the
laboratory, for example, by using energetic lasers. In the astronomical
case, each observation is unique and almost fixed in time, while shocks
produced in the laboratory and by numerical simulations can be reproduced,
and investigated in greater detail. The combined study of experimental and
computational results, as presented here, becomes a unique and powerful
probe to understanding radiative shock physics. Here we show the first
experiment on radiative shock performed at the PALS laser facility. The
shock is driven by a piston made from plastic and gold in a cell filled
with xenon at 0.2 bar. During the first 40 ns of the experiment, we have
traced the radiative precursor velocity, that is showing a strong decrease
at that stage. Three-dimensional (3D) numerical simulations, including
state-of-art opacities, seem to indicate that the slowing down of the
precursor is consistent with a radiative loss, induced by a transmission
coefficient of about 60% at the walls of the cell. We infer that such 3D
radiative effects are governed by the lateral extension of the shock wave,
by the value of the opacity, and by the reflection on the walls. Further
investigations will be required to quantify the relative importance of
each component on the shock properties.