Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mapping the gas kinematics and ionization structure of four
  ultraluminous IRAS galaxies   (Abridged) We analyse the morphology, kinematics and ionization structure of
the extended emission-line regions in four ULIRGs at 0.118<z<0.181, using ARGUS
integral-field spectroscopy. The gas kinematics in the hyperluminous system
IRAS F20460+1925 lack coherent structure, with FWHM>1000 km/s within 1" of the
nucleus; an isolated blob ~8kpc from the nucleus with a much lower FWHM may lie
in a photoionization cone. Line ratios suggest AGN-photoionization for the
systemic gas, and shock+precursor ionization for a second,
spatially-unresolved, nuclear component blueshifted by 990 km/s. The gas in
IRAS F23060+0505 is in dipolar rotation but with an asymmetric rotation curve
and an increased FWHM on one side; an asymmetry to the narrow-line profiles is
attributed to a spatially-resolved outflow, and shock+precursor ionization is
dominant. At lower luminosity, IRAS F01217+0122 has a featureless velocity
field with a high FWHM, an AGN-like emission-line spectrum and a ~1 Gyr old
stellar population. IRAS F01003-2238 has a dipolar velocity field and an
HII-region emission-line spectrum with a strong blue continuum which can be
reproduced with ~10^7 O5 stars, sufficient to account for the bolometric
luminosity of the entire galaxy. This diversity is accommodated within the
merger-driven evolutionary scenario for ULIRGs: the merger status is assessed
from the kinematics in a way which is consistent with the colour and morphology
of the galaxy, or with the inferred age of the stellar population and the
dominance of the AGN.

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The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
2
The categories of this paper are: math
9
The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: cond-mat
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The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci