Kavli Affiliate: Claudio Ricci
| First 5 Authors: Lulu Zhang, Ismael García-Bernete, Chris Packham, Fergus R. Donnan, Dimitra Rigopoulou
| Summary:
We analyze JWST MIRI/MRS IFU observations of three Seyferts and showcase the
intriguing polycyclic aromatic hydrocarbon (PAH) emission characteristics in
regions of $sim 500,rm pc$ scales over or around their active galactic
nuclei (AGN). Combining the model predictions and the measurements of PAH
features and other infrared emission lines, we find that the central regions
containing a high fraction of neutral PAHs with small sizes, e.g., those in
ESO137-G034, are in highly heated environments, due to collisional shock
heating, with hard and moderately intense radiation fields. Such environments
are proposed to be associated with inhibited growth or preferential erosion of
PAHs, decreasing the average PAH size and the overall abundance of PAHs. We
additionally find that the central regions containing a high fraction of
ionized PAHs with large sizes, e.g., those in MCG-05-23-016, are likely
experiencing severe photo-ionization because of the radiative effects from the
radiative shock precursor besides the AGN. The severe photo-ionization can
contribute to the ionization of all PAHs and further destruction of small PAHs.
Overall, different Seyferts, even different regions in the same galaxy, e.g.,
those in NGC,3081, can contain PAH populations of different properties.
Specifically, Seyferts that exhibit similar PAH characteristics to ESO137-G034
and MCG-05-23-016 also tend to have similar emission line properties to them,
suggesting that the explanations for PAH characteristics of ESO137-G034 and
MCG-05-23-016 may also apply generally. These results have promising
application in the era of JWST, especially in diagnosing different (i.e.,
radiative, and kinetic) AGN feedback modes.
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