@article{2022A&A...666A.115P,
 abstract = {Context. Future and ongoing infrared and radio observatories such as
JWST, METIS, and ALMA will increase the amount of rest-frame IR
spectroscopic data for galaxies by several orders of magnitude.
While studies of the chemical composition of the interstellar
medium (ISM) based on optical observations have been widely
spread over decades for star-forming galaxies (SFGs) and, more
recently, for active galactic nuclei (AGN), similar studies need
to be performed using IR data. In the case of AGN, this regime
can be especially useful given that it is less affected by
temperature and dust extinction, traces higher ionic species,
and can also provide robust estimations of the chemical
abundance ratio N/O. \ Aims: We present a new tool
based on a Bayesian-like methodology (HII-CHI-MISTRY-IR) to
estimate chemical abundances from IR emission lines in AGN. We
use a sample of 58 AGN with IR spectroscopic data retrieved from
the literature, composed by 43 Seyferts, eight ultraluminous
infrared galaxies (ULIRGs), four luminous infrared galaxies
(LIRGs), and three low-ionization nuclear emission line regions
(LINERs), to probe the validity of our method. The estimations
of the chemical abundances based on IR lines in our sample are
later compared with the corresponding abundances derived from
the optical emission lines in the same objects. \
Methods: HII-CHI-MISTRY-IR takes advantage of photoionization
models, characterized by the chemical abundance ratios O/H and
N/O, and the ionization parameter U, to compare their predicted
emission-line fluxes with a set of observed values. Instead of
matching single emission lines, the code uses some specific
emission-line ratios that are sensitive to the above free
parameters. \ Results: We report mainly solar and
also subsolar abundances for O/H in the nuclear region for our
sample of AGN, whereas N/O clusters are around solar values. We
find a discrepancy between the chemical abundances derived from
IR and optical emission lines, the latter being higher than the
former. This discrepancy, also reported by previous studies of
the composition of the ISM in AGN from IR observations, is
independent of the gas density or the incident radiation field
to the gas, and it is likely associated with dust obscuration
and/or temperature stratification within the gas nebula.
\\Full Tables A.1-A.4 are only
available at the CDS via anonymous ftp to <A
href=``http://cdsarc.u-strasbg.fr/''>cdsarc.u-strasbg.fr</A>
(ftp://130.79.128.5) or via <A
href=``http://cdsarc.u-strasbg.fr/viz-
bin/cat/J/A+A/666/A115''>http://cdsarc.u-strasbg.fr/viz-
bin/cat/J/A+A/666/A115</A>},
 adsnote = {Provided by the SAO/NASA Astrophysics Data System},
 adsurl = {https://ui.adsabs.harvard.edu/abs/2022A&A...666A.115P},
 archiveprefix = {arXiv},
 author = {Pérez-Dı́az, Borja and Pérez-Montero, Enrique and Fernández-Ontiveros, Juan A. and V\ĺchez, José M.},
 doi = {10.1051/0004-6361/202243602},
 eid = {A115},
 eprint = {2207.08718},
 journal = {åp},
 keywords = {galaxies: abundances, galaxies: active, galaxies: ISM, galaxies: nuclei, infrared: ISM, Astrophysics - Astrophysics of Galaxies},
 month = {October},
 pages = {A115},
 primaryclass = {astro-ph.GA},
 title = {Measuring chemical abundances in AGN from infrared nebular lines: HII-CHI-MISTRY-IR for AGN},
 volume = {666},
 year = {2022}
}