Resolved Dust in z ≈ 1 Galaxies with JWST/MIRI MRS: Survey Description and First View on Polycyclic Aromatic Hydrocarbons, Mid-infrared Atomic Emission, and Warm H 2
Year: 2026
Type: article
Abstract: Dust is a key component of galaxies that regulates their thermal balance and, consequently, star formation and the buildup of stellar mass. Polycyclic aromatic hydrocarbons (PAHs) are responsible for reprocessing the radiative energy of galaxies, thus tracing dust evolution. Using JWST/MIRI Medium Resolution Spectroscopy (MRS), we present the first resolved view of the PAHs and mid-infrared emission lines in a sample of eight z ≈ 1 galaxies. A key novelty is our ability to directly map PAH emission near the end of cosmic noon at JWST’s limits. The sample is selected to be on the star-forming main sequence with stellar masses M ⋆ = 10 10.6−11.2 M ⊙ and infrared luminosities L IR = 10 11.5−11.9 L ⊙ . Two of them contain active galactic nuclei (AGN), and two are interacting systems. We detect and quantify primary PAH emissions from 3.3 to 11.3 μ m throughout the galaxies, alongside atomic fine-structure lines (Ar, Ne, and Fe), Br α , and H 2 rotational transitions. Through PAH ratio diagnostics and comparison to theoretical models, we qualitatively probe the physical properties of PAH molecules, i.e., size and charge. The AGN and mergers in our sample exhibit a higher fraction of neutral PAHs, possibly related to high radiation intensity and/or shocks, as suggested by increased atomic and H 2 line ratios. Leveraging the integral field units data, we find that the grain sizes of the centrally located PAHs tend to be larger and less ionized than those in the outskirts of the galaxies. Finally, we compare our results to observations of PAHs in local and similar-redshift galaxies, revealing a potential evolutionary trend when controlling L IR .
Source: The Astrophysical Journal
Authors: Wuji 无忌 Wang 王, Andreas L. Faisst, Thomas S.-Y. 劭愉 Lai 賴, Kyle Finner, Jed McKinney, Andrew J. Battisti, Irene Shivaei, Leindert A. Boogaard, Daizhong Liu, Yu-Heng Lin, Lun-Jun Liu, Georgios Magdis, Vincenzo Mainieri, Alexander Rodriguez, John D. Silverman, Zhaoxuan Liu, Minju M. Lee, Ghassem Gozaliasl, Maximilien Franco
Institutions: California Institute of Technology, Infrared Processing and Analysis Center, The University of Texas at Austin, Australian National University, The University of Western Australia, Centro de Astrobiología, Leiden University, Chinese Academy of Sciences, University of Copenhagen, Technical University of Denmark, European Southern Observatory, European Southern Observatory, University of Michigan, Johns Hopkins University, The University of Tokyo, Université Paris-Saclay, University of Helsinki, Aalto University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7204773141