ALBERT

Description: The quasar Q0918+1636 ( z = 3.07) has an intervening high-metallicity damped Lyman α absorber (DLA) along the line of sight, at a redshift of z = 2.58. The DLA is located at a large impact parameter of 16.2 kpc, and despite this large impact parameter, it has a very high metallicity (consistent with solar). In this paper, it is investigated whether a novel type of galaxy formation models, based on hydrodynamical/gravitational TreeSPH simulations invoking a new Supernova Type II feedback prescription, the Haardt & Madau most recent ultraviolet background radiation (UVB) field and explicit treatment of UVB self-shielding effects, can reproduce the observed characteristics of the DLA. Effects of UV radiation from young stellar populations in the galaxy, in particular in the photon energy range 10.36–13.61 eV (relating to Sulphur II abundance), are also considered in the analysis. It is found that (a) for L ~ L * galaxies (at z = 2.58), about 10 per cent of the sight-lines through the galaxies at impact parameter b = 16.2 kpc will display a Sulphur II column density of $N(\rm {S\,\small {II})} \ge 10^{15.82}$ cm –2 (the observed value for the DLA), and (b) considering only cases where a near-solar metallicity will be detected at 16.2 kpc impact parameter, the (Bayesian) probability distribution of galaxy star formation rate peaks near the value observed for the DLA galaxy counterpart of $27^{+20}_{-9} {\,\mathrm{M}_{\odot }}$  yr –1 . It is argued that the bulk of the α-elements, like Sulphur, traced by the high metal column density, b = 16.2 kpc absorption lines, have been produced by evolving stars in the inner galaxy, and subsequently transported outwards by galactic winds.