Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gaussian decomposition of HI surveys. IV. Galactic intermediate- and
  high-velocity clouds   Traditionally IVC and HVC were defined to be concentrations of HI gas, with
line-of-sight velocities that are inconsistent with data on the differential
rotation of the Galaxy. We demonstrate that IVCs and HVCs can be identified
from certain density enhancements in (V_C, FWHM) distribution of Gaussians,
representing the Galactic HI 21 cm radio lines. We study the Gaussians, which
parameters fall into the regions of the phase-space density enhancements about
$(V_C, FWHM) = (-131, 27), (164, 26) and (-49 km/s, 23 km/s). The sky
distribution of the Gaussians, corresponding to the first two concentrations,
very well represents the sky distribution of HVCs, as obtained on the basis of
the traditional definition of these objects. The Gaussians of the last
concentration correspond to IVCs. Based on this identification, the division
line between IVCs and HVCs can be drawn at about |V_C| = 74 km/s, and IVCs can
be identified down to velocities of about |V_C| = 24 km/s. Traces of both IVCs
and HVCs can also be seen in the sky distribution of Gaussians with FWHM = 7.3
km/s. In HVCs, these cold cores have small angular dimensions and low observed
brightness temperatures T_b. In IVCs, the cores are both larger and brighter.
This definition of IVCs and HVCs is less dependant than the traditional one, on
the differential rotation model of the Galaxy. The consideration of line-width
information may enable IVCs and HVCs to be better distinguished from each
other, and from the ordinary Galactic HI

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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: econ
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The categories of this paper are: math
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The categories of this paper are: cs
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The categories of this paper are: cmp-lg