Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Monitoring the Variability of Intrinsic Absorption Lines in Quasar
  Spectra   We have monitored 12 intrinsic narrow absorption lines (NALs) in five quasars
and seven mini-broad absorption lines (mini-BALs) in six quasars for a period
of 4-12 years (1-3.5 years in the quasar rest-frame). We present the
observational data and the conclusions that follow immediately from them, as a
prelude to a more detailed analysis. We found clear variability in the
equivalent widths (EWs) of the mini-BAL systems but no easily discernible
changes in their profiles. We did not detect any variability in the NAL systems
nor in narrow components that are often located at the center of mini-BAL
profiles. Variations in mini-BAL EWs are larger at longer time intervals,
reminiscent of the trend seen in variable broad absorption lines. If we assume
that the observed variations result from changes in the ionization state of the
mini-BAL gas, we infer lower limits to the gas density $\sim$ 10$^3$-10$^5$
cm$^{-3}$ and upper limits on the distance of the absorbers from the central
engine of order a few kpc. Motivated by the observed variability properties, we
suggest that mini-BALs can vary because of fluctuations of the ionizing
continuum or changes in partial coverage while NALs can vary primarily because
of changes in partial coverage.

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The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: cs
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The categories of this paper are: comp-gas