Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Beware of fake AGNs   In the BPT diagram, the distribution of the emission-line galaxies from the
Sloan Digital Sky Survey (SDSS) evokes the wings of a seagull. Traditionally,
galaxies in the right wing are considered to host AGNs. Our study of the
stellar populations of SDSS galaxies showed that about1/4 of galaxies thought
to host LINERS are in fact "retired galaxies", i.e. galaxies that stopped
forming stars and are ionized by hot post-AGB stars and white dwarfs (Stasinska
et al. 2008). When including the galaxies that lack some of the lines needed to
place them in the BPT diagram the fraction of retired galaxies is even larger
(Cid Fernandes et al., 2009, arXiv:0912.1376)

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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int