Thomas Lai (Caltech/IPAC): "Probing the Smallest Interstellar Dust Grains with JWST in Different Galaxy"


Dust around active galactic nuclei (AGN) and star-forming regions offers crucial insights into the physical conditions of the ISM. The advent of sensitive, high-resolution infrared integral-field unit (IFU) spectroscopy in the near- and mid-infrared with the James Webb Space Telescope (JWST) has opened up a tremendous opportunity to study the starburst-AGN connection and dust properties in metal-poor systems in nearby galaxies. In this talk, I will present recent results from the GOALS-JWST ERS program 1328 and GO 2511, focusing on NIRSpec and MIRI observations of the type 1 Seyfert galaxy NGC7469 and the metal-poor blue compact dwarf IIZw40, two galaxies with very distinct ISM environments. For NGC7469, the high spatial and spectral resolution of the JWST has enabled us to map the starburst and the region immediately surrounding the AGN and study the dust, ionized atomic gas, and warm molecular gas on 100 pc scales for the first time. Our findings show that the starburst ring exhibits prominent Polycyclic Aromatic Hydrocarbon (PAH) emission, while small grains are heavily processed due to the hard radiation field near the AGN. In contrast, IIZw40 demonstrates the persistence of small grains despite the conventional view that they are rapidly destroyed in low metallicity environments due to harsh radiative conditions. Evidence for the robust detection of small grains in IIZw40 will be presented. Finally, we will compare NGC7469 and IIZw40 to other galaxies measured with NIRSpec and MIRI, and discuss the implications of these results for studies of PAH emission in high-redshift galaxies with JWST.

Date: 12:15 PM, April 10th, 2024
Location: MR-102 and online (Zoom), please join the Caltech/IPAC Seminar Mailing list at https://lists.ipac.caltech.edu/mailman/listinfo/seminars to obtain more information
Category: Science Talk