Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Complex Radio Spectral Energy Distributions in Luminous and
  Ultraluminous Infrared Galaxies   We use the Expanded Very Large Array to image radio continuum emission from
local luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) in 1 GHz
windows centered at 4.7, 7.2, 29, and 36 GHz. This allows us to probe the
integrated radio spectral energy distribution (SED) of the most energetic
galaxies in the local universe. The 4-8 GHz flux densities agree well with
previous measurements. They yield spectral indices \alpha \approx -0.67 (where
F_\nu \propto \nu^\alpha) with \pm 0.15 (1\sigma) scatter, typical of
nonthermal (synchrotron) emission from star-forming galaxies. The contrast of
our 4-8 GHz data with literature 1.5 and 8.4 GHz flux densities gives further
evidence for curvature of the radio SED of U/LIRGs. The SED appears flatter
near \sim 1 GHz than near \sim 6 GHz, suggesting significant optical depth
effects at the lower frequencies. The high frequency (28-37 GHz) flux densities
are low compared to extrapolations from the 4-8 GHz data. We confirm and extend
to higher frequency a previously observed deficit of high frequency radio
emission for luminous starburst galaxies.

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The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
10
The categories of this paper are: q-bio
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The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph