Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spatial Structure and Collisionless Electron Heating in Balmer-dominated
  Shocks   Balmer-dominated shocks in supernova remnants (SNRs) produce strong hydrogen
lines with a two-component profile composed of a narrow contribution from cold
upstream hydrogen atoms, and a broad contribution from hydrogen atoms that have
undergone charge transfer reactions with hot protons. Observations of emission
lines from edge-wise shocks in SNRs can constrain the gas velocity and
collisionless electron heating at the shock front. Downstream hydrogen atoms
engage in charge transfer, excitation and ionization reactions, defining an
interaction region called the shock transition zone. The properties of hot
hydrogen atoms produced by charge transfers (called broad neutrals) are
critical for accurately calculating the structure and radiation from the shock
transition zone. This paper is the third in a series describing the kinetic,
fluid and emission properties of Balmer-dominated shocks, and is the first to
properly treat the effect of broad neutral kinetics on shock transition zone
structure. We use our models to extract shock parameters from observations of
Balmer-dominated SNRs. We find that inferred shock velocities and electron
temperatures are lower than those of previous calculations by <10% for v_s<1500
km/s, and by 10-30% for v_s>1500 km/s. This effect is primarily due to the fact
that excitation by proton collisions and charge transfer to excited levels
favor the high speed part of the neutral hydrogen velocity distribution. Our
results have a strong dependence on the ratio of electron to proton
temperatures, \beta=T_e/T_p, which allows us to construct a relation \beta(v_s)
between the temperature ratio and shock velocity. We compare our calculations
to previous results by Ghavamian et al. (2007).

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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: physics
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: cs
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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: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph