James Webb Space Telescope Feed Post

Arxiv: Blowing star formation away in AGN Hosts (BAH) - II. Investigating the origin of the H2 emission excess in nearby galaxies with JWST MIRI Published: 10/9/2024 5:57:19 PM Updated: 2/17/2025 8:33:21 PM

Paper abstract: We use James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI)medium-resolution spectrometer (MRS) observations of 3C 293 (UGC 8782), CGCG012-070 and NGC 3884 to investigate the origin of the H_2 emission. Thesethree nearby Active Galactic Nucleus (AGN) hosts are known to present H_2emission excess relative to star-forming galaxies, as traced by the H_2S(3)/PAH_{\rm 11.3\mu m} line ratio. We define the kinematically disturbedregion (KDR) by the AGN and the virially dominated region (VDR) based on theH_2 line widths, using the W{\rm 80} parameter. From the correlationsbetween W{\rm 80} and H_2 S(3)/PAH{\rm 11.3\mu m}, as well as the higherH2 S(5)/H2 S(3) and [Fe II]{\rm 5.34 \mu m}/PAH{\rm 11.3\mu m} ratiosand flatter power-law temperature distributions observed in the KDR, weconclude that the H_2 emission in the KDR is primarily driven by shock-heatedgas. For 3C 293, the KDR is co-spatial with the radio core, indicating that theorigin of the shocks is the interaction of the radio jet with the interstellarmedium, which is also responsible for the observed molecular and ionized gasoutflows in this source. The other galaxies are weak radio sources; however,due to the lack of high-resolution radio images, we cannot rule out low-powerjets as the origin of the shock-heated H_2. Our results indicate that theexcess 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 ambientgas.