Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Ultraviolet Emission Properties of Five Low-Redshift Active Galactic
  Nuclei at High Signal to Noise and Spectral Resolution   We analyze the ultraviolet (UV) emission line and continuum properties of
five low-redshift active galactic nuclei (four luminous quasars:
PKS~0405$-$123, H1821+643, PG~0953+414, and 3C273, and one bright Seyfert 1
galaxy: Mrk~205). The HST spectra have higher signal-to-noise ratios (typically
$\sim 60$ per resolution element) and spectral resolution ($R = 1300$) than all
previously- published UV spectra used to study the emission characteristics of
active galactic nuclei. We include in the analysis ground-based optical spectra
covering \hb\ and the narrow [O III] $\lambda\lambda$4959,5007 doublet. The
following new results are obtained: \lyb/\lya=0.03$-$0.12 for the four quasars,
which is the first accurate measurement of the long-predicted \lyb\ intensity
in QSOs. The cores of \lya\ and C~IV are symmetric to an accuracy of better
than
  2.5% within about 2000 km s$^{-1}$ of the line peak. This high degree of
symmetry of \lya\ argues against models in which the broad line cloud velocity
field has a significant radial component. The observed smoothness of the \lya\
and C~IV line profiles requires at least $\sim 10^4$ individual clouds if bulk
velocity is the only line-broadening mechanism. The overall similarity of the
\lya\ and C IV $\lambda$1549 profiles rules out models for the broad line
region (BLR) with a radial distribution of virialized....

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The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
1
The categories of this paper are: cs
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
2
The categories of this paper are: math