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Abstract:

We summarise the properties of the absorbing haloes around two high-redshift radio galaxies studied with the VLT-UVES echelle spectrograph. The absorbers in 0943 - 242 (z = 2.92) exhibit little further structure compared with previous data-the main absorber still has N(HI) similar or equal to 10(19) cm(-2)-reinforcing the picture in which the absorbing gas occupies a smooth shell beyond the emission line halo. In 0200+015 (z = 2.23) the main absorber now splits into two spatially-resolved systems with N(HI) = 4 x 10(14) cm(-2), one of which has strong CIV absorption, implying a metallicity of Z similar or equal to 10 Zcircle dot. We explain the differences between the two sources with an evolutionary scenario, invoking interaction with the expanding radio source and metal enrichment via a starburst superwind. (C) 2003 Elsevier B.V. All rights reserved.

Abstract:

As a prerequisite for cosmological studies using adaptive optics techniques, we have begun to identify and characterize faint sources in the vicinity of bright stars at high Galactic latitudes. The initial phase of this work has been a program of K_s imaging conducted with SOFI at the ESO NTT. From observations of 42 southern fields evenly divided between the spring and autumn skies, we have identified 391 additional stars and 1589 galaxies lying at separations 60" from candidate guide stars in the magnitude range 9.0 R 12.4. When analyzed as a "discrete deep field" with 131 arcmin^2 area, our dataset gives galaxy number counts that agree with those derived previously over the range 16 K_s 20.5. This consistency indicates that in the aggregate, our fields should be suitable for future statistical studies. We provide our source catalogue as a resource for users of large telescopes in the southern hemisphere.