Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Structure of the X-ray Emission from the Jet of 3C 273   We present images from five observations of the quasar 3C 273 with the
Chandra X-ray Observatory. The jet has at least four distinct features which
are not resolved in previous observations. The first knot in the jet (A1) is
very bright in X-rays. Its X-ray spectrum is well fitted with a power law with
alpha = 0.60 +/- 0.05. Combining this measurement with lower frequency data
shows that a pure synchrotron model can fit the spectrum of this knot from
1.647 GHz to 5 keV (over nine decades in energy) with alpha = 0.76 +/- 0.02,
similar to the X-ray spectral slope. Thus, we place a lower limit on the total
power radiated by this knot of 1.5e43 erg/s; substantially more power may be
emitted in the hard X-ray and gamma-ray bands.
  Knot A2 is also detected and is somewhat blended with knot B1. Synchrotron
emission may also explain the X-ray emission but a spectral bend is required
near the optical band. For knots A1 and B1, the X-ray flux dominates the
emitted energy. For the remaining optical knots (C through H), localized X-ray
enhancements that might correspond to the optical features are not clearly
resolved. The position angle of the jet ridge line follows the optical shape
with distinct, aperiodic excursions of +/-1 deg from a median value of
-138.0deg. Finally, we find X-ray emission from the ``inner jet'' between 5 and
10" from the core.

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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-th