Energetic winds and radiation from massive star clusters push the surrounding gas and blow superbubbles in the interstellar medium ( ISM ) .
Using 1-D hydrodynamic simulations , we study the role of radiation in the dynamics of superbubbles driven by a young star cluster of mass 10 ^ { 6 } M _ { \odot } .
We have considered a realistic time evolution of the mechanical power as well as radiation power of the star cluster , and detailed heating and cooling processes .
We find that the ratio of the radiation pressure on the shell ( shocked ISM ) to the thermal pressure ( \sim 10 ^ { 7 } K ) of the shocked wind region is almost independent of the ambient density , and it is greater than unity before \lesssim 1 Myr .
We explore the parameter space of density and dust opacity of the ambient medium , and find that the size of the hot gas ( \sim 10 ^ { 7 } K ) cavity is insensitive to the dust opacity ( \sigma _ { d } \approx ( 0.1 - 1.5 ) \times 10 ^ { -21 } cm ^ { 2 } ) , but the structure of the photoionized ( \sim 10 ^ { 4 } K ) gas depends on it .
Most of the radiative losses occur at \sim 10 ^ { 4 } K , with sub-dominant losses at \lesssim 10 ^ { 3 } K and \sim 10 ^ { 6 } -10 ^ { 8 } K. The superbubbles can retain as high as \sim 10 \% of its input energy , for an ambient density of 10 ^ { 3 } m { { } _ { H } cm ^ { -3 } } .
We discuss the role of ionization parameter and recombination-averaged density in understanding the dominant feedback mechanism .
Finally , we compare our results with the observations of 30 Doradus .