Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Halo properties and secular evolution in barred galaxies   The halo plays a crucial role in the evolution of barred galaxies. Its
near-resonant material absorbs angular momentum emitted from some of the disc
particles and helps the bar become stronger. As a result, a bar (oval) forms in
the inner parts of the halo of strongly barred disc galaxies. It is thinner in
the inner parts (but still considerably fatter than the disc bar) and tends to
spherical at larger radii. Its length increases with time, while always staying
shorter than the disc bar. It is roughly aligned with the disc bar, which it
trails only slightly, and it turns with roughly the same pattern speed. The
bi-symmetric component of the halo density continues well outside the halo bar,
where it clearly trails behind the disc bar. The length and strength of the
disc and halo bars correlate; the former being always much stronger than the
latter. If the halo is composed of weakly interacting massive particles, then
the formation of the halo bar, by redistributing the matter in the halo and
changing its shape, could influence the expected annihilation signal. This is
indeed found to be the case if the halo has a core, but not if it has a steep
cusp. The formation and evolution of the bar strongly affect the halo orbits. A
fraction of them becomes near-resonant, similar to the disc near-resonant
orbits at the same resonance, while another fraction becomes chaotic. Finally,
a massive and responsive halo makes it harder for a central mass concentration
to destroy the disc bar.

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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: hep-th
3
The categories of this paper are: physics
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The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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The categories of this paper are: q-alg
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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: chem-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: bayes-an