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We present new Keck/HIRES data of the most metal-poor damped Lyman-alpha(DLA) system currently known. By targeting the strongest accessible Fe IIfeatures, we have improved the upper limit of the [Fe/H] abundancedetermination by ~1 dex, finding [Fe/H]<-3.66 (2 sigma). We also provide thefirst upper limit on the relative abundance of an odd-atomic number element forthis system [Al/H]<-3.82 (2 sigma). Our analysis thus confirms that thisz_abs=3.07 DLA is not only the most metal-poor DLA but also the most iron-poorDLA currently known. We use the chemistry of this DLA, combined with astochastic chemical enrichment model, to probe its enrichment history. We findthat this DLA is best modelled by the yields of an individual Population IIIprogenitor rather than multiple Population III stars. We then draw comparisonswith other relic environments and, particularly, the stars within nearbyultra-faint dwarf galaxies. We identify a star within Bootes I, with a similarchemistry to that of the DLA presented here, suggesting that it may have beenborn in a gas cloud that had similar properties. The extremely metal-poor DLAat redshift z_abs=3.07 (i.e. ~2 Gyrs after the Big Bang) may reside in one ofthe least polluted environments in the early Universe.

Towards ultra metal-poor DLAs: linking the chemistry of the most metal-poor DLA to the first stars