Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: H-alpha Spectroscopy of Galaxies at z>2: Kinematics and Star Formation   We present near-infrared spectroscopy of H-alpha emission lines in a sample
of 16 star-forming galaxies at redshifts 2.0<z<2.6. Our targets are drawn from
a large sample of galaxies photometrically selected and spectroscopically
confirmed to lie in this redshift range. Six of the galaxies exhibit spatially
extended, tilted H-alpha emission lines; rotation curves for these objects
reach mean velocities of ~150 km/s at radii of ~6 kpc, without corrections for
any observational effects. The velocities and radii give a mean dynamical mass
of M>4e10 M_sun. One-dimensional velocity dispersions for the 16 galaxies range
from ~50 to ~260 km/s, and in cases where we have both virial masses implied by
the velocity dispersions and dynamical masses derived from the spatially
extended emission lines, they are in rough agreement. We compare our kinematic
results to similar measurements made at z~3, and find that both the observed
rotational velocities and velocity dispersions tend to be larger at z~2 than at
z~3. We find a mean SFR_H-alpha of 16 M_sun/yr and an average
SFR_H-alpha/SFR_UV ratio of 2.4, without correcting for extinction. We see
moderate evidence for an inverse correlation between the UV continuum
luminosity and the ratio SFR_H-alpha/SFR_UV, such as might be observed if the
UV-faint galaxies suffered greater extinction. We discuss the effects of dust
and star formation history on the SFRs, and conclude that extinction is the
most likely explanation for the discrepancy between the two SFRs.

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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: stat