2001A&A...370..426D

We present the first high-resolution (6.2 to 7.7km/s FWHM) spectra of the APM BR J0307-4945 quasar at z_em=4.73 obtained with UVES on the 8.2m VLT Kueyen telescope. We focus our analysis on a damped Lyα (DLA) system at z_abs=4.466 with a neutral hydrogen column density N(HI)=(4.68±0.97)x10²⁰cm^–2. It is the most distant DLA system known to the present date, observed when the age of the universe was only 1.3Gyr. It shows complex low- and high-ionization line profiles spanning ≃240 and 300km/s in velocity space respectively. We derive accurate abundances for N, O, Al, Si and Fe, and place a lower limit on C and an upper limit on Ni: [N/H]=-3.07±0.15, [O/H]=-1.63±0.19, [Al/H]=-1.79±0.11, [Si/H]=-1.54±0.11, [Fe/H]=-1.97±0.19, [C/H]>-1.63 and [Ni/H]←2.35. The derived high metallicity, ∼1/90 solar, shows that this very young absorber (≤1.3Gyr) has already experienced a significant metal enrichment. The [O/Si] ratio is nearly solar suggesting a limited amount of dust, the relative [Si, O/Fe] abundance ratios show a similar enhancement as observed in the Milky Way stars with comparable metallicities, and the [N/O] ratio is very low. All these results point to an enrichment pattern dominated by type II supernovae which suggests a Milky Way type evolutionary model.