2014ApJ...784...93Z

Galactic superwinds may be driven by very hot outflows generated by overlapping supernovae within the host galaxy. We use the Chevalier & Clegg (CC85) wind model and the observed correlation between X-ray luminosities of galaxies and their star formation rates (SFRs) to constrain the mass-loss rates ({dot}M_hot) across a wide range of SFRs, from dwarf starbursts to ultraluminous infrared galaxies. We show that for fixed thermalization and mass-loading efficiencies, the X-ray luminosity of the hot wind scales as L_X∝SFR², significantly steeper than is observed for star-forming galaxies: L_X∝SFR. Using this difference, we constrain the mass-loading and thermalization efficiency of hot galactic winds. For reasonable values of the thermalization efficiency ( ≲ 1) and for SFR ≳ 10 M_☉/yr we find that {dot}M_hot/ SFR ≲ 1, which is significantly lower than required by integrated constraints on the efficiency of stellar feedback in galaxies and potentially too low to explain observations of winds from rapidly star-forming galaxies. In addition, we highlight the fact that heavily mass-loaded winds cannot be described by the adiabatic CC85 model because they become strongly radiative.