Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectral indices of Galactic radio loops between 1420, 820 and 408 MHz   In this paper the average brightness temperatures and surface brightnesses at
1420, 820 and 408 MHz of the six main Galactic radio-continuum loops are
derived, as are their radio spectral indices. The temperatures and surface
brightnesses of the radio loops are computed using data taken from radio
continuum surveys at 1420, 820 and 408 MHz. We have demonstrated the reality of
Loops V and VI and present diagrams of their spectra for the first time. We
derived the radio spectral indices of Galactic radio loops from radio surveys
at three frequencies (1420, 820 and 408 MHz) and confirm them to be non-thermal
sources. Diameters and distances of Loops I-VI were also calculated. The
results obtained are in good agreement with current theories of supernova
remnant (SNR) evolution and suggest that radio loops may have a SNR origin.

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The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: solv-int
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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: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: cond-mat
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The categories of this paper are: econ