Hot galactic winds constrained by the X-ray luminosities of galaxies

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 (Ṁhot) 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 asL_X SFR₂, significantly steeper than is observed for starforming 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 10Ṁ;yr ^-1 we find that Ṁhot/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.