  We find a bright (L_{UV}=2.5 L*_{z=6}) Lyman alpha emitter at redshift
z=5.719 at a projected distance of 79 physical kpc from a strong triply ionized
carbon (Civ) absorption system at redshift z=5.7238 previously reported in the
spectrum of the z_{em} = 6.309 QSO SDSS J1030+0524. This is the highest
redshift galaxy-absorber pair detected to-date, supporting the idea that
galaxy-wide outflows were already in place at the end of the epoch of
reionization. The proximity of this object makes it the most likely source of
metals, consistent with models of outflows at lower redshift where significant
observational evidence relates metal absorption systems with galaxies hosting
outflows.
  In a typical outflow scenario, a wind of 200 km/s, active since the universe
was only 0.6 Gyr old (z ~8.4), could eject metals out to 79 kpc at z=5.719.
Although the origin of metals in the intergalactic medium (IGM) is still under
debate, our results are consistent with predictions from cosmological
simulations which reproduce the evolution of the cosmic density of Civ, from z
~ 6 to the present day based on outflow-driven enrichment of the IGM.
  We also report two more Lyman alpha emitters in this field, at z=5.973\pm
0.002 and z=5.676\pm 0.002 respectively, the former confirming the original
identification by Stiavelli et al. Our results suggest that the colour cut
typically used to identify i-dropouts (i_{775}-z_{850}>1.3) misses a
non-negligible fraction of blue galaxies with faint UV continuum at z \geq 5.7.

Cosmology and Nongalactic Astrophysics;Astrophysics of Galaxies