Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Nature of Velocity Fields in High z Galaxies   We analyze the gas kinematics of damped Lya systems (DLAs) hosting high z
gamma-ray bursts (GRBs) and those toward quasars (QSO-DLAs) focusing on
threestatistics: (1) dv, the velocity interval encompassing 90% of the
totaloptical depth, (2,3) Wsi and Wciv, the rest equivalent widths of the
SiII1526 and CIV1548 transitions. The dv distributions of the GRB-DLAs and
QSO-DLAs are similar, each has median dv~80km/s and a significant tail to
several hundred km/s. This suggests comparable galaxy masses for the parent
populations of GRB-DLAs and QSO-DLAs and we infer the average dark matter halo
mass of GRB galaxies is <~10^{12} Msol. The unique configuration of GRB-DLA
sightlines and the presence (and absence) of fine-structure absorption together
give special insight into the nature of high z, protogalactic velocity fields.
The data support a scenario where the dv statistic reflects dynamics in the
interstellar medium (ISM) and Wsi traces motions outside the ISM (e.g. halo
gas, galactic-scale winds). The Wsi statistic and gas metallicity [M/H] are
tightly correlated, especially for the QSO-DLAs: [M/H]=a + b log(Wsi/1A) with
a=-0.92+/-0.05 and b=-1.41+/-0.10. We argue that the Wsi statistic primarily
tracks dynamical motions in the halos of high z galaxies and interpret this
correlation as a mass-metallicity relation with very similar slope to the trend
observed in local, low-metallicity galaxies. Finally, the GRB-DLAs exhibit
systematically larger Wsi values (>0.5A) than the QSO-DLAs (<Wsi>~ 0.5A) which
may suggest galactic-scale outflows contribute to the largest observed velocity
fields.

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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas