Metal and dust evolution in ALMA REBELS galaxies: insights for future JWST observations

Marco Palla, Ilse De Looze, Monica Relaño, Stefan van der Giessen, Pratika Dayal, Andrea Ferrara, Raffaella Schneider, Luca Graziani, Hiddo S. B. Algera, Manuel Aravena, Rebecca A. A. Bowler, Alexander P. S. Hygate, Hanae Inami, Ivana van Leeuwen, Rychard Bouwens, Jacqueline Hodge, Renske Smit, Mauro Stefanon, Paul van der Werf

Published 2023-11-27Version 1

ALMA observations revealed the presence of significant amounts of dust in the first Gyr of Cosmic time. However, the metal and dust buildup picture remains very uncertain due to the lack of constraints on metallicity. JWST has started to reveal the metal content of high-redshift targets, which may lead to firmer constraints on high-redshift dusty galaxies evolution. In this work, we use detailed chemical and dust evolution models to explore the evolution of galaxies within the ALMA REBELS survey, testing different metallicity scenarios that could be inferred from JWST observations. In the models, we track the buildup of stellar mass by using non-parametric SFHs for REBELS galaxies. Different scenarios for metal and dust evolution are simulated by allowing different prescriptions for gas flows and dust processes. The model outputs are compared with measured dust scaling relations, by employing metallicity-dependent calibrations for the gas mass based on the [CII]158micron line. Independently of the galaxies metal content, we found no need for extreme dust prescriptions to explain the dust masses revealed by ALMA. However, different levels of metal enrichment will lead to different dominant dust production mechanisms, with stardust production dominant over other ISM dust processes only in the metal-poor case. This points out how metallicity measurements from JWST will significantly improve our understanding of the dust buildup in high-redshift galaxies. We also show that models struggle to reproduce observables such as dust-to-gas and dust-to-stellar ratios simultaneously, possibly indicating an overestimation of the gas mass through current calibrations, especially at high metallicities.