Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Simultaneous UV and X-ray Spectroscopy of the Seyfert 1 Galaxy NGC 5548.
  I. Physical Conditions in the UV Absorbers   We present new UV spectra of the nucleus of the Seyfert 1 galaxy NGC 5548,
which we obtained with the Space Telescope Imaging Spectrograph at high
spectral resolution, in conjunction with simultaneous Chandra X-ray Observatory
spectra. Taking advantage of the low UV continuum and broad emission-line
fluxes, we have determined that the deepest UV absorption component covers at
least a portion of the inner, high-ionization narrow-line region (NLR). We find
nonunity covering factors in the cores of several kinematic components, which
increase the column density measurements of N V and C IV by factors of 1.2 to
1.9 over the full-covering case; however, the revised columns have only a minor
effect on the parameters derived from our photoionization models. For the first
time, we have simultaneous N V and C IV columns for component 1 (at -1040
km/s), and find that this component cannot be an X-ray warm absorber, contrary
to our previous claim based on nonsimultaneous observations. We find that
models of the absorbers based on solar abundances severely overpredict the O VI
columns previously obtained with the Far Ultraviolet Spectrograph, and present
arguments that this is not likely due to variability. However, models that
include either enhanced nitrogen (twice solar) or dust, with strong depletion
of carbon in either case, are successful in matching all of the observed ionic
columns. These models result in substantially lower ionization parameters and
total column densities compared to dust-free solar-abundance models, and
produce little O VII or O VIII, indicating that none of the UV absorbers are
X-ray warm absorbers.

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The categories of this paper are: solv-int
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
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The categories of this paper are: eess
21
The categories of this paper are: adap-org
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The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
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The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc