ﻻ يوجد ملخص باللغة العربية
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 correspondingly massive black holes. [...] In this study, we exploit the opportunity to eliminate the quasar glare by performing sensitive spectropolarimetry with the Keck II telescope of a sample of radio galaxies with redshifts around 2.5. [...] We show that dust-reflected quasar light generally dominates the restframe ultraviolet continuum of these sources and that a highly clumped scattering medium results in almost grey scattering of the active galactic nucleus photons. The observations, however, do not exclude a substantial star formation rate averaged over a Gyr of evolution. The sub-mm reradiation from the scattering dust is likely to represent only a small fraction (~10%) of the total far infrared luminosity. An analysis of the emission lines excited in the interstellar medium of the host galaxy by the hard quasar radiation field reveals evidence of a dramatic chemical evolution within the spheroid during this epoch. Secondary nitrogen production in intermediate mass stars produces a characteristic signature in the NV/CIV and NV/HeII line ratios which has been seen previously in the broad line region of quasars at similar redshifts. We find intriguing correlations between the strengths of the Ly alpha and NV emission lines and the degree of ultraviolet continuum polarization which may represent the dispersal of dust associated with the chemical enrichment of the spheroid.
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
We report ESO-VLT near-infrared adaptive optics imaging of one radio-loud (PKS 0113-283) and two radio-quiet (Q 0045-3337 and Q 0101-337) QSOs at z > 2. In the first case, we are able to resolve the QSO and find that it is hosted by an elliptical of
We present the results of NICMOS imaging of two massive galaxies photometrically selected to have old stellar populations at z ~ 2.5. Both galaxies are dominated by apparent disks of old stars, although one of them also has a small bulge comprising a
We present preliminary results on 24micron detections of luminous infrared galaxies at z>1 with the Multiband Imaging Photometer for Spitzer (MIPS). Observations were performed in the Lockman Hole and the Extended Groth Strip (EGS), and were suppleme
Spatially resolved velocity profiles are presented for nine faint field galaxies in the redshift range 0.1 < z < 1, based on moderate-resolution spectroscopy obtained with the Keck 10 m telescope. These data were augmented with high-resolution HST im