Abstract
We present results on the spectroscopic study of the extended ionized gas in the distant radio galaxy USS0828+193 at z =2.57. The kinematic analysis of the Keck II spectra reveals the existence of a giant ( ~ 80 kpc) low surface brightness halo of quiescent kinematics consistent with gravitational motions. The halo is enriched with heavy elements and is ionized by the continuum from the active nucleus. We find similar halos in most objects in our sample of 11 high redshift (z ~ 2.5) radio galaxies. They might be a common ingredient of this type of objects. We discuss briefly the nature and the origin of these halos.
