Chandra reveals a double-sided X-ray jet in the quasar 3C9 at z=2.012
  A Chandra observation of the radio-loud quasar 3C9 at redshift z=2.012 has revealed extended X-ray emission coincident with the radio jet. Of particular interest is the appearance of both jet and counterjet, which argues against the X-ray emission being highly beamed. We present the properties of the jets and discuss possible scenarios for the X-ray emission, contrasting them with the single sided jet found in PKS 0637-752, which has a similar X-ray luminosity. The jet X-ray emission in 3C9 is likely to be due to either nonthermal emission from a sheath with bulk Lorentz factor less than 1.5, or thermal emission from shocked cold gas surrounding the quasar. The thermal possibility implies a high mass for the cold gas unless it is highly clumped. 
A.C. Fabian (IOA), A. Celotti (SISSA) and R.M. Johnstone (IOA)