Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinematics and dynamics of relativistic jets on large and small scales   Modelling of deep VLA images of the jets in FR I radio galaxies has allowed
us to derive their three-dimensional distributions of velocity, emissivity and
magnetic-field structure on kiloparsec scales. By combining our models of jet
kinematics with measurements of the external pressure and density derived from
Chandra observations, we can also determine the jet dynamics via a
conservation-law approach. The result is a detailed and quantitative picture of
jet deceleration. We discuss the potential application of these techniques on
VLBI scales. Our fundamental assumption is that the jets are intrinsically
symmetrical, axisymmetric, relativistic flows. Although this is likely to be a
good approximation on average, the effects of non-stationarity in the flow
(e.g. shocks/knots) may limit its applicability on pc scales. We also stress
the need for both the main and counter-jet to be detected with good transverse
resolution in linear polarization as well as total intensity. Two foreground
effects (free-free absorption and Faraday rotation) must also be corrected. We
comment on the implications of observed VLBI polarization and Faraday rotation
for the field structure (and, by implication, collimation) of pc-scale jets.
Where our VLA observations start to resolve the jets, about 1 kpc from the
nucleus, they are travelling at about 0.8c. We briefly discuss the deceleration
of jets from a much faster initial speed.

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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: q-bio
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The categories of this paper are: physics
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph