Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Formation and evolution of interstellar filaments; Hints from velocity
  dispersion measurements   We investigate the gas velocity dispersions of a sample of filaments recently
detected as part of the Herschel Gould Belt Survey in the IC5146, Aquila, and
Polaris interstellar clouds. To measure these velocity dispersions, we use
13CO, C18O, and N2H+ line observations obtained with the IRAM 30m telescope.
Correlating our velocity dispersion measurements with the filament column
densities derived from Herschel data, we show that interstellar filaments can
be divided into two regimes: thermally subcritical filaments, which have
transonic velocity dispersions (c_s ~< \sigma_tot < 2 c_s) independent of
column density, and are gravitationally unbound; and thermally supercritical
filaments, which have higher velocity dispersions scaling roughly as the square
root of column density (\sigma_tot ~ \Sigma^0.5), and are self-gravitating. The
higher velocity dispersions of supercritical filaments may not directly arise
from supersonic interstellar turbulence but may be driven by gravitational
contraction/accretion. Based on our observational results, we propose an
evolutionary scenario whereby supercritical filaments undergo gravitational
contraction and increase in mass per unit length through accretion of
background material while remaining in rough virial balance. We further suggest
that this accretion process allows supercritical filaments to keep their
approximately constant inner widths (~ 0.1 pc) while contracting.

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The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat
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The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat