Heating and Ionization of the Primordial Intergalactic Medium by High
  Mass X-ray Binaries
  We investigate the influence of High Mass X-ray Binaries on their high
redshift environments. Using a one-dimensional radiative transfer code, we
predict the ionization and temperature profiles surrounding a coeval stellar
population, composed of main sequence stars and HMXBs, at various times after
its formation. We consider both uniform density surroundings, and a cluster
embedded in a 10^8 solar mass NFW halo. HMXBs in a constant density environment
produce negligible enhanced ionization because of their high-energy SEDs and
short lifetimes. In this case, HMXBs only marginally contribute to the local
heating rate. For NFW profiles, radiation from main sequence stars cannot
prevent the initially ionized volume from recombining since it is unable to
penetrate the high density galactic core. However, HMXB photons stall
recombinations behind the front, keeping it partially ionized for longer. The
increased electron density in these partially ionized regions promotes further
cooling, resulting in lower IGM temperatures. In the context of this starburst
model, we have shown that HMXBs do not make a major contribution to
reionization or IGM heating. However, X-ray escape fractions are high in both
density profile cases. Continuous star formation may result in the build up of
X-rays over time, reducing the ionization timescale and potentially leading to
low level ionization of the distant IGM.
