Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical integral field spectroscopy of the extended line emission around
  six radio-loud quasars   We present integral field spectroscopy of a small sample of radio-loud
quasars at intermediate redshift (0.26<z<0.60), most of which are associated
with large radio sources. All have oxygen line emission extended over tens of
kiloparcsecs, and these nebulae display a diverse range in both morphology and
kinematic behaviour. Two quasars show 'plumes' of extended line emission, two
show a clumpy structure and a further one shows a smooth distribution. There is
no clear pattern with regard to the distribution of the ionized gas in relation
to the radio source axis; the extended emission-line regions are found both
parallel and perpendicular - and also totally unrelated to - the radio axis.
The velocity structure of the ionized gas ranges from essentially static to
apparent smooth rotation, and in two cases, show a clear association with the
radio source. Given the disparity in properties, the nebulae all show a
surprisingly similar ionization state, as measured by the extended lines of
[OII] and [OIII]. Assuming the gas is ionized by at least the nearby quasar
nucleus, we use the emission line ratios to infer a pressure in the ionized
gas; in all cases we find it to be at high pressure, suggesting confinement by
an external (probably intracluster) medium.

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The categories of this paper are: math
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol