Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Crab Nebula: interpretation of CHANDRA observations   We interpret the observed X-ray morphology of the central part of the Crab
Nebula (torus + jets) in terms of the standard theory by Kennel and Coroniti
(1984). The only new element is the inclusion of anisotropy in the energy flux
from the pulsar in the theory. In the standard theory of relativistic winds,
the Lorentz factor of the particles in front of the shock that terminates the
pulsar relativistic wind depends on the polar angle as
$\gamma=\gamma_0+\gamma_m\sin^2\theta$, where $\gamma_0 \sim 200$ and $\gamma_m
\sim 4.5\times 10^6$. The plasma flow in the wind is isotropic. After the
passage of the pulsar wind through the shock, the flow becomes subsonic with a
roughly constant (over the plerion volume) pressure $P={1\over 3}n\epsilon$,
where $n$ is the plasma particle density and $\epsilon$ is the mean particle
energy. Since $\epsilon \sim \gamma mc^2$, a low-density region filled with the
most energetic electrons is formed near the equator. A bright torus of
synchrotron radiation develops here. Jet-like regions are formed along the
pulsar rotation axis, where the particle density is almost four orders of
magnitude higher than that in the equatorial plane, because the particle energy
there is four orders of magnitude lower. The energy of these particles is too
low to produce detectable synchrotron radiation. However, these quasi-jets
become comparable in brightness to the torus if additional particle
acceleration takes place in the plerion. We also present the results of our
study of the hydrodynamic interaction between an anisotropic wind and the
interstellar medium. We compare the calculated and observed distributions of
the volume intensity of X-ray radiation.

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The categories of this paper are: eess
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat