Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Elemental Abundances in Two High Column Density Damped Lyman Alpha
  Systems at z < 1.5   We present Keck/HIRES abundance measurements and metal-line kinematic
profiles of the damped Lyman alpha systems (DLAs) towards the quasars Q0933+733
(z_abs=1.479) and Q0948+433 (z_abs=1.233). These two DLAs have among the five
highest HI column densities at any redshift: N(HI)=4.2E21 cm^{-2}. The
metal-line data, presented here for the first time, reveal that these DLAs are
noteworthy for several other reasons as well. 1) The Q0933+733 DLA exhibits
simple kinematic structure with unusually narrow velocity widths as measured
from its unsaturated metal lines (delta v=16 km/s). At 2.6% solar, it has the
second lowest metallicity at z<2. 2) The Q0948+433 DLA has among the strongest
metal-line transitions of any known DLA. The saturated SiII1808 line implies a
high metallicity ([Si/H]> -1) and a significant alpha-enhancement. The strong
metal lines of this DLA have made possible the detection of TiII1910, CoII2012,
and MgI2026. 3) We find that the relative gas-phase abundances of both DLAs
follow the general trend seen at high redshift, e.g., enhanced Zn/Fe and Si/Fe,
and sub-solar Mn/Fe, indicating that there is little evolution in the
nucleosynthetic patterns of DLAs down to this epoch. 4) Their high HI column
densities imply that these DLAs dominate the column density-weighted cosmic
mean metallicity, <Z>, of the universe at z<1.5. Using the 15 DLAs with
measured metallicities in the redshift interval 0.4<z<1.5, we find <Z> =
-0.89^{+0.40}_{-0.33}, where the uncertainties are 95% confidence limits.

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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex