Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Bar Signature and Central Disk in the Gaseous and Stellar Velocity
  Fields of NGC5448   We analyse SAURON kinematic maps of the inner kpc of the early-type (Sa)
barred spiral galaxy NGC5448. The observed morphology and kinematics of the
emission-line gas is patchy and perturbed, indicating clear departures from
circular motion. The kinematics of the stars is more regular, and display a
small inner disk-like system embedded in a large-scale rotating structure. We
focus on the [OIII] gas, and use a harmonic decomposition formalism to analyse
the gas velocity field. The higher-order harmonic terms and the main kinematic
features of the observed data are consistent with an analytically constructed
simple bar model. The bar model is derived using linear theory, considering an
m=2 perturbation mode, and with bar parameters which are consistent with the
large-scale bar detected via imaging. We also study optical and near infra-red
images to reveal the asymmetric extinction in NGC5448, and we recognise that
some of the deviations between the data and the analytical bar model may be due
to these complex dust features. Our study illustrates how the harmonic
decomposition formalism can be used as a powerful tool to quantify non-circular
motions in observed gas velocity fields.

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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: math
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: econ