  We use hydrodynamical models of the wind-collision region (WCR) in the
archetype colliding-wind system WR140 to determine the spatial and spectral
distribution of the radio, X-ray and gamma-ray emission from shock accelerated
electrons. Our calculations are for orbital phase 0.837 when the observed radio
emission is close to maximum. Using the observed thermal X-ray emission
together with the radio emission to constrain the mass-loss rates, we find that
the O-star mass-loss rate is consistent with recent reductions for O4-5
supergiants. We demonstrate that radio VLBI observations of the WCR fail to
constrain the opening angle. The observed low frequency turnover at ~3 GHz in
the radio emission is due to free-free absorption, since models based on the
Razin effect have an unacceptably large fraction of energy in non-thermal
particles. The index of the non-thermal electron energy distribution is flatter
than the canonical value for diffusive shock acceleration, namely p<2. Several
mechanisms are discussed that could lead to such an index. Tighter constraints
on p and the nature of the shocks in WR140 will be obtained from future
observations at MeV and GeV energies, for which we generally predict lower
fluxes than previous work. Since the high stellar photon fluxes prevent the
acceleration of electrons beyond gamma > 1e5-1e6, TeV emission from CWB systems
will provide unambiguous evidence of pion-decay emission from accelerated ions.
We finish by commenting on the emission and physics of the multiple wind
collisions in dense stellar clusters, paying particular attention to the
Galactic Centre (abridged).
