Galactic wind X-ray heating of the intergalactic medium during the Epoch
  of Reionization
  The diffuse soft X-ray emissivity from galactic winds is computed during the
Epoch of Reionization (EoR). We consider two analytic models, a pressure-driven
wind and a superbubble model, and a 3D cosmological simulation including gas
dynamics from the First Billion Years (FiBY) project. The analytic models are
normalized to match the diffuse X-ray emissivity of star-forming galaxies in
the nearby Universe. The cosmological simulation uses physically motivated star
formation and wind prescriptions, and includes radiative transfer corrections.
The models and the simulation all are found to produce sufficient heating of
the Intergalactic Medium to be detectable by current and planned radio
facilities through 21 cm measurements during the EoR. While the analytic models
predict a 21 cm emission signal relative to the Cosmic Microwave Background
sets in by $z_{\rm trans} \simeq 8 - 10$, the predicted signal in the FiBY
simulation remains in absorption until reionization completes. The 21 cm
absorption differential brightness temperature reaches a minimum of $\Delta T
\simeq -130$ to $-200$ mK, depending on model. Allowing for additional heat
from high mass X-ray binaries pushes the transition to emission to $z_{\rm
trans} \simeq 10 - 12$, with shallower absorption signatures having a minimum
of $\Delta T \simeq -110$ to $-140$ mK. The 21 cm signal may be a means of
distinguishing between the wind models, with the superbubble model favouring
earlier reheating. While an early transition to emission may indicate X-ray
binaries dominate the reheating, a transition to emission as early as $z_{\rm
trans} > 12$ would suggest the presence of additional heat sources.
