Revealing the routes for dust evolution in star-forming and quiescent galaxies at z >1-6: observations vs. models

Although a significant number of dust-rich galaxies have been confirmed in the distant Universe (up to z~7), the origin of their dust reservoirs remains one of the major open questions in the theory of galaxy formation. With the advent of ALMA and JWST, observational studies are able to infer the dust-to-stellar mass ratio as one of key observable markers to probe how the efficiencies of dust production and destruction in dusty galaxies evolve from early cosmic times to the "cosmic noon". These studies revealed surprising results, such that the dust-to-stellar mass ratio varies over 2-3 orders of magnitude not only in star-forming galaxies (SFGs), but also in high-z quiescent galaxies (QGs) of comparable stellar masses. The discoveries pose important questions, e.g. can cosmological simulations and models explain observed dust-to-stellar mass ratios simultaneously for SFGs and QGs? Are physical mechanisms attributed to the dust abundance in both galaxy populations of the same origin?

This walk will show the findings of two studies that analyze the evolution of the dust-to-stellar mass ratio in observable and simulated galaxies at 1 < z < 6. To interpret the complex evolution of dust-to-stellar mass ratio with observed redshifts, galaxy sizes and stellar masses, we utilize the chemical and analytical models as well as the full suite of SIMBA cosmological simulation. I will first explain how to account for observational biases to ensure accurate comparison between observations and models. Owing to a remarkable match with SIMBA predictions, I will present how the dust-rich galaxies at high-z result from diverse formation redshifts and transition through different dust evolution pathways. The observed abundances in SFGs (QGs) at high-z cannot be explained if dust is solely due to ongoing (past) star formation. I will illustrate how, contrary to some claims, the feedback modes attributed to the AGN are not impacting the dust and cold gas within the same timescales. This reflects the key role of rapid dust re-growth in metal-rich environments, which can create variations in dust-to-stellar mass ratios through the AGN feedback cycle. I will demonstrate how this complicates the conventional view in which dust and molecular gas mass mirror each other's evolution and sharply decline with increasing stellar age. In this context, I will quickly discuss major implications for the future observational efforts with JWST and ALMA seeking to identify larger number of dusty galaxies below the main sequence at z > 1-6.