  The evolution of X-ray emission from young massive star clusters is modeled,
taking into account the emission from the stars as well as from the cluster
wind. It is shown that the level and character of the soft (0.2-10 keV) X-ray
emission change drastically with cluster age and are tightly linked with
stellar evolution. Using the modern X-ray observations of massive stars we show
that the correlation between bolometric and X-ray luminosity known for single O
stars also holds for O+O and O+Wolf-Rayet (WR) binaries. The diffuse emission
originates from the cluster wind heated by the kinetic energy of stellar winds
and supernova explosions. To model the evolution of the cluster wind, the mass
and energy yields from a population synthesis are used as input to a
hydrodynamic model. It is shown that in a very young clusters the emission from
the cluster wind is low. When the cluster evolves, WR stars are formed. Their
strong stellar winds power an increasing X-ray emission of the cluster wind.
Subsequent supernova explosions pump the level of diffuse emission even higher.
Clusters at this evolutionary stage may have no X-ray bright stellar point
sources, but a relatively high level of diffuse emission. A supernova remnant
may become a dominant X-ray source, but only for a short time interval of a few
thousand years. We retrieve and analyse Chandra and XMM-Newton observations of
six massive star clusters located in the Large Magellanic Cloud. Our model
reproduces the observed diffuse and point-source emission from these LMC
clusters, as well as from the Galactic clusters Arches, Quintuplet and NGC
3603.
