The infrared signatures of very small grains in the Universe seen by JWST

TL;DR

This paper discusses how JWST will enhance the study of infrared signatures of very small grains and PAHs in the universe, enabling analysis of previously unresolved sources and their physical and chemical properties.

Contribution

It introduces the potential of JWST to extend spectral studies of PAHs and eVSGs to new astronomical sources with higher sensitivity and resolution.

Findings

JWST will improve detection of IR signatures in distant galaxies.

Spectral variations relate to local physical conditions.

Analysis can reveal chemical composition of small grains.

Abstract

The near- and mid-IR spectrum of many astronomical objects is dominated by emission bands due to UV-excited polycyclic aromatic hydrocarbons (PAH) and evaporating very small grains (eVSG). Previous studies with the ISO, Spitzer and AKARI space telescopes have shown that the spectral variations of these features are directly related to the local physical conditions that induce a photo-chemical evolution of the band carriers. Because of the limited sensitivity and spatial resolution, these studies have focused mainly on galactic star-forming regions. We discuss how the advent of JWST will allow to extend these studies to previously unresolved sources such as near-by galaxies, and how the analysis of the infrared signatures of PAHs and eVSGs can be used to determine their physical conditions and chemical composition.