Dust and PAHs in late-stage galaxy evolution: Imprints of TP-AGB dust injection, grain growth and AGN feedback in high-z quiescent galaxies with JWST and ALMA
Year: 2026
Type: preprint
Abstract: A major unknown in late-stage galaxy evolution is what regulates the cold interstellar medium (ISM) after quenching, a question central to interpreting molecular gas, dust, and stellar content in quiescent galaxies (QGs) now probed by ALMA and JWST to $z\sim7$. We present the first semi-analytic model that follows the coupled post-quenching evolution of dust, cold gas, and polycyclic aromatic hydrocarbons (PAHs), using flexible star-formation histories and a framework tracking small and large carbonaceous and silicate grains. At $z\sim1$, we find that QGs of similar mass ($M_\star\sim8\times10^{10} M_\odot$), stellar-population age ($\sim2$ Gyr), and cold gas fractions ($f_{\rm gas}\sim1$-$10\%$), span $2$-$3$ dex in $M_{\rm dust}/M_\star$ and $M_{\rm dust}/M_{\rm gas}$, ranging from star-forming-like ratios to highly depleted dust states. The diversity arises from delayed dust injection by thermally pulsing asymptotic giant branch (TP-AGB) stars and ISM grain growth, which sustain dust enrichment for up to $\sim2.5$ Gyr after quenching. Without these channels, the pre-quenching $M_{\rm dust}$ falls below $10\%$ of its initial value within $\lesssim0.5$-$1$ Gyr, and twice as fast when AGN feedback is active. The imprint of post-quenching dust processing persists in substantial reservoirs of small carbonaceous grains, with PAH fractions of $\sim2$-$3\%$, even if the cold-dust budget falls below typical ALMA continuum detection limits ($M_{\rm dust}/M_\star\lesssim10^{-4}$). Such signatures may remain detectable with JWST/MIRI at $μ$Jy depths, probing chemically enriched dust phases in otherwise ALMA-faint galaxies. Altogether, dust and PAHs provide independent probes of distinct stages of ISM evolution in QGs, rather than simply tracing the residual cold ISM of the preceding star-forming phase.
Source: arXiv (Cornell University)
Institutions: National Centre for Nuclear Research, Collurania Teramo Observatory, National Institute for Astrophysics, University of Massachusetts Amherst, University of British Columbia, California Institute of Technology, Infrared Processing and Analysis Center, Scuola Internazionale Superiore di Studi Avanzati, Institute for Fundamental Physics of the Universe, Centro de Astrobiología, Max Planck Institute for Radio Astronomy, University of Nova Gorica
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, National Aeronautics and Space Administration, National Radio Astronomy Observatory, Korea Astronomy and Space Science Institute, Narodowe Centrum Nauki, National Astronomical Observatory of Japan, Istituto Nazionale di Fisica Nucleare, Narodowa Agencja Wymiany Akademickiej, National Science and Technology Council, Natural Sciences and Engineering Research Council of Canada, National Institutes of Natural Sciences
OpenAlex ID: W7204762444