Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A dichotomy in the orientation of dust and radio jets in nearby
  low-power radio galaxies   We examine the properties of central dust in nearby quiescent and active
early-type galaxies. The active galaxies are low-power radio galaxies with
Fanaroff & Riley Type I or I/II radio jets. We focus on the comparison of the
dust distributions in the active and quiescent galaxy samples and the relation
between the radio jet and dust orientations. Our main observational conclusions
are: (a) radio galaxies contain a higher fraction of regular dust 'ellipses'
compared to quiescent galaxies which contain more often irregular dust
distributions; (b) the morphology, size and orientation of dust ellipses and
lanes in quiescent early-types and active early-types with kpc-scale radio jets
is very similar; (c) dust ellipses are aligned with the major axis of the
galaxy, dust lanes do not show a preferred alignment except for large (>kpc)
dust lanes which are aligned with the minor axis of the galaxy. Dust
morphologies can be classified as regular 'ellipses' and filamentary 'lanes'.
We show that the dust ellipses are consistent with being nearly circular thin
disks viewed at random viewing angles. The lanes are likely warped dust
structures, which may be in the process of settling down to become regular
disks or are being perturbed by a non-gravitational force. We use the observed
dust-jet orientations to constrain the three-dimensional angle $\theta_{\rm
DJ}$ between jet and dust. For dust-lane galaxies, the jet is approximately
perpendicular to the dust structure, while for dust-ellipse galaxies there is a
much wider distribution of $\theta_{\rm DJ}$. We discuss two scenarios that
could explain the dust/jet/galaxy orientation dichotomy. (abridged)

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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
0
The categories of this paper are: hep-ph
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The categories of this paper are: supr-con
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: math
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The categories of this paper are: hep-lat
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The categories of this paper are: physics
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: econ