0.5 Mpc-scale extended X-ray emission in the z=2.48 radio galaxy 4C 23.56

We present an XMM-Newton observation of the radio galaxy 4C 23.56 at z = 2.48 which reveals extended X-ray emission coincident with the radio lobes spanning similar to 0.5 Mpc. These are the largest X-ray-bright lobes known at z > 2. Under the assumption that these features result from inverse-Compton scattering of cosmic microwave background photons by relativistic electrons in the radio source lobes, the measured luminosity of L0.5-8 keV = 7.5 x 10(44) erg s(-1) implies that minimum energy stored within the lobes is similar to 10(59) erg. We discuss the potential of the large-scale radio/X-ray lobes to influence evolution of the host galaxy and protocluster environment at high redshift.