Probing the absorbing haloes around two high-redshift radio galaxies with VLT-UVES★.

We present VLT-UVES echelle spectroscopy of the H I and C IV absorption in the spatially extended Lyα emission around two high-redshift radio galaxies 0200 + 015 (z = 2.23) and 0943-242 (z = 2.92). The absorbers in 0943-242 exhibit little additional structure compared with previous lowresolution spectroscopy and the main absorber is still consistent with a H I column density of ∼ 10[sup 19] cm[sup -2]. This is consistent with a picture in which the absorbing gas has low density and low metallicity and is distributed in a smooth absorbing shell located beyond the emission-line gas. However, the main absorbers in 0200 + 015 are very different. The previous single-absorber fit of H I column density ...10[sup 19] cm[sup -2] now splits into two ∼4 × 10[sup 14] cm[sup -2] absorbers which extend more than 15 kpc to obscure additional Lyα emission coincident with a radio lobe in these high-resolution observations. Although consistent with the shell-like distribution for the absorption systems, 0200 + 015 requires a much higher metal enrichment than 0943-242. The metallicity, inferred from the C IV absorption, is considerably lower in 0943-242 than in 0200 + 015. We explain these differences with an evolutionary scenario based on the size of the radio source. In both sources the H I absorption gas originates from either a gas-rich merger or pristine cluster gas which cools and collapses towards the centre of the dark matter halo. The higher metallicity in the larger radio source (0200 + 015) may be a result of a starburst-driven superwind (concurrent with the triggering of the radio emission) which has engulfed the outer halo in this older source. We also find a significant blue asymmetry in the He II λ 1640 emission line, suggesting that the line-emitting gas is outflowing from the central regions. Dust obscuration toward the central engine, presumably due to the dusty toms invoked in the unified scheme, prevents us from seeing outflow... [ABSTRACT FROM AUTHOR]