Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Metallicity measurements in AGNs   Measuring metallicity in the nuclear regions of AGNs is difficult because
only a few lines are observed and ionization correction becomes a major
problem. Nitrogen to carbon ratio has been widely used as an indicator for
metallicity, but precise measurements have been lacking. We made such
measurements for the first time using a wide baseline of ionization states with
observations from FUSE, HST and Chandra. OVI observations with FUSE were
crucial in this effort. We measured super-solar metallicities in two AGNs and
found that N/C does not scale with metallicity. This suggests that chemical
enrichment scenario in nuclear regions of galaxies may be different from
traditional models of metal enrichment.

2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org