Direct-method validation of LINER photoionisation models

Construct a LINER control sample with direct-method ionic abundances and use it to determine whether the sulphur-to-oxygen differences inferred from the adopted photoionisation models represent genuine physical distinctions or limitations of those models.

Background

The AGN model configuration used for the MaNGA analysis was calibrated against a Seyfert control sample with electron-temperature-based ionic abundances. No equivalent LINER benchmark is available, so the same model family has not been independently validated for LINER ionisation conditions.

The authors identify direct-method measurements of LINERs as necessary for testing whether the observed abundance offsets are physical or are caused by inappropriate ionising continua or geometrical prescriptions. Such a sample would provide an observational benchmark analogous to the one used for Seyfert nuclei.

References

In particular, a control sample analogous to that used for Seyfert nuclei, but composed of LINERs with direct-method ionic abundances, would provide a crucial benchmark for determining whether the differences observed here arise from genuine physical distinctions or from limitations in the adopted photoionisation models.

— HII-CHI-mistry for active galactic nuclei: optical sulphur abundances without empirical ionisation correction factors  (2608.25919 - Pérez-Montero et al., 26 Aug 2026) in Section 4.2, “The ionising SED of LINERs”; Section 5, “Summary and conclusions”