Astronomy Colloquium

Dust is sculpted by the processes of galaxy evolution. In this talk, I will present two arguments for the astrophysical importance of dust processing in the interstellar medium (ISM) and implications for interpretation of dust observables in galaxies across cosmic time. First, I will draw on recent data from JWST, SPHEREx, and other facilities to paint the emerging picture of polycyclic aromatic hydrocarbon (PAH) growth in galaxies via gas-phase processes. Implications for the rise of PAHs in galaxies at high redshift (z~7) will be explored. Second, I will argue against the "silicate" and "carbonaceous" dichotomy of interstellar dust grains and present the "astrodust" model in which pristine stardust becomes rapidly homogenized in the ISM. Finally, I will highlight how PRIMA, the recently selected far-infrared Probe mission, will employ spectroscopic observations of PAH and metal line emission and imaging polarimetry of the dust continuum to understand how dust and metals evolve in galaxies over cosmic time.