On the rapidly cooling interior of supergalactic winds

The steady state numerical solution and two dimensional hydrodynamic calculations of supergalactic winds generated by super star clusters are presented. Two possible regimes: quasi-adiabatic and strongly radiative are thoroughly discussed. It is shown that superwinds driven by compact and powerful starbursts undergo catastrophic cooling close to their sources, and establish a temperature distribution radically different from those obtained in the adiabatic solution. At the same time, both velocity and density radial distributions remain almost unchanged given the speed of the rapidly diverging flow. The rapid fall in temperature as a function of radius reduces the size of the zone radiating in X-rays and decreases the superwind X-ray luminosity. At the same time, cooling brings the 10$^4$ K boundary closer to the wind center, and promotes the establishment of an extended ionized fast moving envelope. This should show up as a weak and broad ($\sim 1000$ km s$^{-1}$) line emission component at the base of the much narrower line caused by the central HII region.