X-rays and gamma-rays from the first luminous objects

The first supernovae to explode at high-redshift also accelerated relativistic electrons. Due to the high energy density of the CMB U-CMB proportional to (1 + z)(4), these electrons cool via inverse Compton scattering, generating X-rays. Unlike stellar UV photons, these X-rays can escape easily from the host halo. This results in important differences from canonical reionization scenarios: (i) reionization becomes more homogeneous (ii) increased reheating of the IGM (iii) increased Hz production and cooling. Observations of radio synchrotron emission at high redshift with the Square Kilometer Array carl confirm the presence of relativistic electrons. This mechanism may be responsible for the observed gamma-ray background. GLAST can potentially detect high-redshift blazars out to the epoch of reionization. Pair production opacity to gamma-rays will result in an observable absorption edge, thereby constraining the strength of high-redshift radiation fields.