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We present the results of deep spectropolarimetry of two powerful radio galaxies at $zsim2.5$ (4C 00.54 and 4C 23.56) obtained with the W.M. Keck II 10m telescope, aimed at studying the relative contribution of the stellar and non-stellar components to the ultraviolet continuum. Both galaxies show strong linear polarization of the continuum between rest-frame $sim$1300-2000~AA, and the orientation of the electric vector is perpendicular to the main axis of the UV continuum. In this sense, our objects are like most 3C radio galaxies at $zsim1$. The total flux spectra of 4C 00.54 and 4C 23.56 do not show the strong P-Cygni absorption features or the photospheric absorption lines expected when the UV continuum is dominated by young and massive stars. The only features detected can be ascribed to interstellar absorptions by SiII, CII and OI. Our results are similar to those for 3C radio galaxies at lower $z$, suggesting that the UV continuum of powerful radio galaxies at $zsim2.5$ is still dominated by non-stellar radiation, and that young massive stars do not contribute more than $approx$50% to the total continuum flux at 1500~AA.
We present near-infrared imaging and spectroscopic observations of two FR II high-redshift radio galaxies (HzRGs), 4C 40.36 (z=2.3) and 4C 39.37 (z=3.2), obtained with the Hubble, Keck, and Hale Telescopes. High resolution images were taken with filt
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 ~0.5 Mpc. These are the largest X-ray-bright lobes known at z>2. Under the assumption that thes
In classifying the ensemble of powerful extragalactic radio sources, considerable evidence has accumulated that radio galaxies and quasars are orientation-dependent manifestations of the same parent population: massive spheroidal galaxies containing
We present a study of the gas kinematics of star-forming galaxies associated with protocluster 4C 23.56 at $z=2.49$ using $0.4$ resolution CO (4-3) data taken with ALMA. Eleven H$alpha$ emitters (HAEs) are detected in CO (4-3), including six HAEs tha
We report the discovery of a significant excess of candidate Halpha emitters (HAEs) in the field of the radio galaxy 4C 23.56 at z=2.483. Using the MOIRCS near-infrared imager on the Subaru Telescope we found 11 candidate emission-line galaxies to a