Xray observations of high redshift radio galaxies
  I summarize Xray properties of high redshift radio galaxies, beginning with a brief review of what has been learned from Xray observations of low redshift powerful radio galaxies (in particular, Cygnus A), and then turning to Chandra observations of four high redshift radio galaxies. Hot Xray emitting atmospheres of the type seen in low redshift clusters are not detected in the high redshift sources, suggesting that these systems are not yet virialized massive clusters, but will likely evolve into such. Xray emission from highly obscured AGN is detected in all cases. Extended Xray emission is also seen, and the extended emission is clearly aligned with the radio source, and on a similar spatial scale. Multiple mechanisms are proposed for this radio-Xray alignment, including inverse Compton scattering of photons from the AGN (the 'Brunetti mechanism'), and thermal emission from ambient gas that is shocked heated by the expanding radio source. The pressure in the high filling factor shocked gas is adequate to confine the radio source and the low filling factor optical line emitting clouds. 
C.L. Carilli (NRAO)