@inproceedings{2022eas..conf..720F,
 abstract = {We present a new method to derive heavy element abundances in star
forming galaxies using the unique suite of nebular lines in the
mid- to far-infrared (IR) range. Using grids of photo-ionisation
models that cover a wide range in O/H and N/O, and ionisation
parameter, HII-CHI-MISTRY-IR (HCm-IR) provides abundances based
on extinction-free and temperature-insensitive tracers, two
significant advantages over optical diagnostics when these are
applied to dust obscured regions or unresolved (stratified)
nebulae. The code performance is probed using three different
galaxy samples covering a wide range in metallicity, 7.2 < 12 +
log(O/H) < 8.9, with available IR spectroscopy from Spitzer,
Herschel and SOFIA, including: 28 low-metallicity dwarf
galaxies, 19 nearby starbursts, and 9 luminous IR galaxies. The
IR-based abundances are robust even when the hydrogen
recombination lines, typically faint in this range, are not
available. When compared to various optical-based methods, HCm-
IR is consistent within an average difference of 0.1 dex and a
scatter of 0.2 dex. Additionally, HCm-IR provides an independent
N/O measurement when [OIII]52,88\textmum and
[NIII]57\textmum are measured, probing the secondary
production of nitrogen. We find systematically lower N/O IR
abundances when compared to the optical determinations,
suggesting that IR lines may trace higher excitation gas located
closer to massive stars. Finally, we applied the code to a
sample of 8 distant galaxies located at 1.8 < z < 7.5 with
ground-based detections of the far-IR lines redshifted in the
submm range, revealing sub-solar N/O and O/H abundances. The
script to derive chemical abundances with HCm-IR is publicly
available.},
 adsnote = {Provided by the SAO/NASA Astrophysics Data System},
 adsurl = {https://ui.adsabs.harvard.edu/abs/2022eas..conf..720F},
 author = {Fernández Ontiveros, Juan Antonio and Pérez Montero, Enrique and Pérez-Dı́az, Borja and V\ĺchez, José Manuel and Amor\',́ Ricardo and Spinoglio, Luigi and Malkan, Matthew A. and Pereira-Santaella, Miguel},
 booktitle = {EAS2022, European Astronomical Society Annual Meeting},
 eid = {720},
 month = {July},
 pages = {720},
 title = {Metallicities and N/O abundances in star forming galaxies measured with infrared nebular lines},
 year = {2022}
}