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Harvard ADS: Blowing star formation away in AGN Hosts (BAH) -- II. Investigating the origin of the H2 emission excess in nearby galaxies with JWST MIRI

Paper abstract: We use James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) medium-resolution spectrometer (MRS) observations of UGC 8782, CGCG 012-070 and NGC 3884 to investigate the origin of the H_2 emission. These three nearby AGN hosts are known to present H_2 emission excess relative to star-forming galaxies, as traced by the H_2 S(3)/PAH_{\rm 11.3\mu m} line ratio. For every spaxel, we also measure the velocity width (W_{\rm 80}) of H_2 S(3). We find that the distribution of H_2 in the space of these parameters - H_2/PAH and its velocity width - is bimodal: one cluster of points shows approximately constant values of W_{\rm 80}, while the other cluster exhibits a strong correlation between W_{\rm 80} and H_2/PAH. We estimated the temperature of the H_2 gas assuming a power-law distribution and find flatter distributions in regions where a correlation between W_{\rm 80} and H_2 S(3)/PAH_{\rm 11.3\mu m} is observed. Additionally, we observed a correlation between the [Fe II]_{\rm 5.34 \mu m} (a known shock tracer) and the H_2 emission. This indicates that the excess H_2 emission excess is associated to shock heating of the gas, generated by outflows or by the interaction of the radio jet with the ambient gas.