On the Rapidly Cooling Interior of Supergalactic Winds

The steady state numerical solution and two dimensional hydrodynamiccalculations of supergalactic winds generated by super star clusters arepresented. Two possible regimes: quasi-adiabatic and strongly radiative arethoroughly discussed. It is shown that superwinds driven by compact and powerful starbursts undergocatastrophic cooling close to their sources, and establish a temperaturedistribution radically different from those obtained in the adiabatic solution.At the same time, both velocity and density radial distributions remain almostunchanged given the speed of the rapidly diverging flow. The rapid fall in temperature as a function of radius reduces the size of thezone radiating in X-rays and decreases the superwind X-ray luminosity. At thesame time, cooling brings the 10$^4$ K boundary closer to the wind center, andpromotes the establishment of an extended ionized fast moving envelope. Thisshould show up as a weak and broad ($\sim 1000$ km s$^{-1}$) line emissioncomponent at the base of the much narrower line caused by the central HIIregion.Comment: 7 pages, 6 figures, Accepted for publication in The Astrophysical Journa