Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory of gyroresonance and free-free emissions from non-Maxwellian
  quasi-steady-state electron distributions   Currently there is a concern about ability of the classical thermal
(Maxwellian) distribution to describe quasi-steady-state plasma in solar
atmosphere including active regions. In particular, other distributions have
been proposed to better fit observations, for example, kappa- and
$n$-distributions. If present, these distributions will generate radio
emissions with different observable properties compared with the classical
gyroresonance (GR) or free-free emission, which implies a way of remote
detecting these non-Maxwellian distributions in the radio observations. Here we
present analytically derived GR and free-free emissivities and absorption
coefficients for the kappa- and $n$-distributions and discuss their properties,
which are in fact remarkably different from each other and from the classical
Maxwellian plasma. In particular, the radio brightness temperature from a
gyrolayer increases with the optical depth $\tau$ for kappa-distribution, but
decreases with $\tau$ for $n$-distribution. This property has a remarkable
consequence allowing a straightforward observational test: the gyroresonance
radio emission from the non-Maxwellian distributions is supposed to be
noticeably polarized even in the optically thick case, where the emission would
have strictly zero polarization in the case of Maxwellian plasma. This offers a
way of remote probing the plasma distribution in astrophysical sources
including solar active regions as a vivid example.

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The categories of this paper are: comp-gas
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The categories of this paper are: stat
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
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The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: chao-dyn