2011MNRAS.412.1047C

We present high-resolution observations of an extremely metal-poor damped Lyα system (DLA), at z_abs= 2.340 0972 in the spectrum of the QSO J0035-0918, exhibiting an abundance pattern consistent with model predictions for the supernova yields of Population III stars. Specifically, this DLA has [Fe/H]≃-3, shows a clear `odd-even' effect, and is C-rich with [C/Fe]=+1.53, a factor of ∼20 greater than reported in any other DLA. In analogy to the carbon-enhanced metal-poor stars in the Galactic halo (with [C/Fe] > +1.0), this is the first known case of a carbon-enhanced DLA. We determine an upper limit to the mass of <sup>12</sup>C, M(<sup>12</sup>C) ≤ 200 M<sub>☉</sub>, which depends on the unknown gas density n(H); if n(H) > 1/cm3 (which is quite likely for this DLA given its low velocity dispersion), then M(<sup>12</sup>C) ≤ 2 M<sub>☉</sub>, consistent with pollution by only a few prior supernovae. We speculate that DLAs such as the one discovered here may represent the `missing link' between the yields of Population III stars and their later incorporation in the class of carbon-enhanced metal-poor stars which show no enhancement of neutron-capture elements (CEMP-no stars).

Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.