Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Synchrotron radiation and absence of linear polarization in the
  colliding wind binary WR 146   Several massive early-type binaries exhibit non-thermal emission which has
been attributed to synchrotron radiation from particles accelerated by
diffusive shock acceleration (DSA) in the wind-collision region (WCR). If the
magnetic field in the strong shocks is ordered, its component parallel to the
shock front should be enhanced, and the resultant synchrotron radiation would
be polarized. However, such polarization has never been measured. We performed
spatially-unresolved radio continuum observations of WR 146, a well known a
WC6+O8 system, at 5 cm and 20 cm with the Karl G. Jansky Very Large Array. No
linearly polarized radio emission was detected. The data constrain the
fractional linear polarization to less than 0.6% between 1 to 8 GHz. This is
compatible with a high level of turbulence and a dominant random component in
the magnetic field. In this case the relativistic particles could be produced
by turbulent magnetic reconnection (MR). In order for this scenario to satisfy
the required non-thermal energy budget, we find through numerical modeling that
the strength of the magnetic field in the WCR must be as high as ~150 mG.
However, if the magnetic field is ordered and DSA is ongoing, then a
combination of internal and external Faraday rotation could equally account for
the depolarization of the emission. It is not clear whether it is possible to
develop the high level of turbulence and strong magnetic fields required for
efficient MR in a long-period binary such as WR 146. This scenario might also
have trouble explaining the low-frequency cutoff in the spectrum. We therefore
favor a scenario where particles are accelerated through DSA and the
depolarization is produced by mechanisms other than a large ratio between
random to regular magnetic fields.

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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: physics
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The categories of this paper are: supr-con
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys