Tilman Hartwig

The generation and evolution of dust in galaxies are important tracers for star formation, and can characterize the rest-frame ultraviolet to infrared emission from the galaxies. In particular understanding dust in high-redshift galaxies are important for observational cosmology, as they would be necessary to extract information on star formation in the early Universe. We update the public semi-analytical model Ancient Stars and Local Observables by Tracing Halos (a-sloth) to model the evolution of dust, focusing on high-redshift star-forming galaxies with stellar masses of ∼108–1010 M⊙ observed by ALMA (z ≈ 7) and JWST (z ≈ 11). We find that these galaxies should qualitatively differ in their star formation properties; while the samples in ALMA are explained by dust growth in normal star-forming galaxies, the lack of dust in the samples by JWST requires dust ejection by radiation pressure due to recent highly efficient star formation within a few 10 Myr, with order 100 times higher efficiency than normal galaxies calibrated by a-sloth. Depending on where the JWST galaxies locate on the luminosity function, their bursty star formation histories inferred from our model can have impacts for rates of star formation, supernova explosion, stellar feedback, and detectability of dusty, mature galaxies in the very early Universe.