Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The temperature of the WNM in the Milky Way   We report high spectral resolution Australia Telescope Compact Array HI 21 cm
observations resulting in the detection of the warm neutral medium (WNM) of the
Galaxy in absorption against two extragalactic radio sources, PKS 1814-637 and
PKS 0407-658. The two lines of sight were selected on the basis of the
simplicity of their absorption profiles and the strength of the background
sources; the high velocity resolution of the spectra then enabled us to
estimate the kinetic temperatures of the absorbing gas by fitting multiple
Gaussians to the absorption profiles. Four separate WNM components were
detected toward the two sources, with peak optical depths $\tau_{max} = (1.0
\pm 0.08) \times 10^{-2}$, $(1.4 \pm 0.2) \times 10^{-3}$, $(2.2 \pm 0.5)
\times 10^{-3}$ and $(3.4 \pm 0.5) \times 10^{-3}$ and kinetic temperatures
$T_{k} = 3127 \pm 300$ K, $3694 \pm 1595$ K, $3500 \pm 1354$ K and $2165 \pm
608$ K respectively. All four components were thus found to have temperatures
in the thermally unstable range $500 < T_{k} < 5000$ K; this suggests that
thermal equilibrium has not been reached throughout the WNM.

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The categories of this paper are: comp-gas
16
The categories of this paper are: stat
18
The categories of this paper are: econ
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
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The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs