The dust enrichment of early galaxies in the JWST and ALMA era

Recent observations with the JWST are yielding tantalizing hints of an early population of massive, bright galaxies at z > 10, with Atacama Large Millimeter/submillimeter Array (ALMA) observations indicating significant dust masses as early as z similar to 7. To understand the implications of these observations, we use the delphi semi-analytic model that jointly tracks the assembly of dark matter haloes and their baryons, including the key processes of dust enrichment. Our model employs only two redshift- and mass-independent free parameters (the maximum star formation efficiency and the fraction of supernova energy that couples to gas) that are tuned against all available galaxy data at z similar to 5-9 before it is used to make predictions up to z similar to 20. Our key results are: (i) the model underpredicts the observed ultraviolet luminosity function (UV LF) at z > 12, observations at z > 16 lie close to, or even above, a 'maximal' model where all available gas is turned into stars; (ii) UV selection would miss 34 per cent of the star formation rate density at z similar to 5, decreasing to 17 per cent by z similar to 10 for bright galaxies with ; (iii) the dust mass (M-d) evolves with the stellar mass (M-*) and redshift as log(M-d) = 1.194log(M) + 0.0975z - 5.433; (iv) the dust temperature increases with stellar mass, ranging between 30 and 33 K for M-* similar to 10(9-11) M-circle dot galaxies at z similar to 7. Finally, we predict the far-infrared LF at z similar to 5-20, testable with ALMA observations, and caution that spectroscopic redshifts and dust masses must be pinned down before invoking unphysical extrema in galaxy formation models.