Lunch talk on Oct. 17, 2022

Decoding Interstellar Dust and Polycyclic Aromatic Hydrocarbons (PAHs) in the JWST Era

Speaker: Dangning Hu (CEA-Saclay)

Venue: Video Conference

Time: 12:30 PM, Monday, Oct. 17, 2022

Abstract: 

The knowledge of interstellar dust is crucial to understanding numerous physical processes in galaxies. Mid-infrared (MIR) spectra contain the most solid-state resonance features of interstellar grains, including the unidentified infrared bands (UIBs) ranging from 3.3 to 17 microns. They arise from a statistical mixing of polycyclic aromatic hydrocarbons (PAHs) of different sizes and structures. I have developed a new spectral decomposition software, MILES, to perform a state-of-the-art observational study of UIBs observed by the Spitzer (IRS; 5.2 - 38 microns) and AKARI (IRC; 2.5 - 5 microns) satellites. This code applies the hierarchical Bayesian inference to simultaneously model heterogeneous samples of nearby galaxies. I will present how to link the spatial variations of MIR features to the physical conditions of interstellar PAHs (ionization, size distribution, dehydrogenation, etc.). The method is apt for the observations of JWST, which have a spectroscopic capability (NIRSpec: 0.6 - 5 microns; MIRI: 5 - 27 microns) covering the entire spectral range of the UIBs, along with unprecedented resolutions and sensitivity.

Report PPT:  SWIFAR_Dangning_Hu.pdf