Relativistic X-ray jets at high redshift

Abstract

Powerful radio sources and quasars emit relativistic jets of plasma and magnetic fields that travel hundreds of kiloparsecs, ultimately depositing energy into the intra- or inter-cluster medium. In the rest frame of the jet, the energy density of the cosmic microwave background is enhanced by the bulk Lorentz factor as Γ 2 , and when this exceeds the magnetic energy density the primary loss mechanism of the relativistic electrons is via inverse Compton scattering. The microwave energy density is also enhanced by a factor (1 + z) 4 , which becomes important at large redshifts. We are surveying a z > 3 subsample of radio sources selected with centimeter-wavelength flux density >70 mJy, and with a spectroscopic redshift. Out of the first 12 objects observed, there are two clear cases of the X-rays extending beyond the detectable radio jet.