| Gas and dust are fundamental components of galaxies and the cycle of exchanging material between stars, interstellar gas and cosmic dust is key for the chemical enrichment of the ISM/CGM. Metals are missing from the observable ISM gas phase because they are instead incorporated into dust grains, an effect we call dust depletion. This effect alters the observed chemical abundances, which can be inferred through absorption-line spectroscopy. Characterizing the dust depletion of metals both in the local and distant Universe is important to investigate the evolution and origin of metals and dust through cosmic time. In my talk, I will present how we can use dust depletion to estimate key properties of dust, such as the dust-to-metal (DTM) and dust-to-gas (DTG) ratios and dust composition in different galactic environments, including the Milky Way, the Magellanic Clouds, and damped Lyman-alpha absorbers (DLAs) towards quasars (QSOs) and towards gamma-ray bursts (GRBs). How is dust produced and eventually destroyed? How are metals distributed in the gas surrounding galaxies and is their distribution different for different galactic environments? Finally, I will present a novel method to estimate the depletion of metals into dust using the relative abundances of metals, which we call dust tracers. This method is free of the caveats that previous methods face and can be applied in diverse galactic environments and cosmic times. How do different dust tracers correlate with each other? How can column densities of metals be used to estimate the overall strength of depletion per line-of-sight? How can the overall strength of depletion be used to estimate the depletion of different elements into dust? How can the chemical enrichment of the ISM/CGM be traced using dust depletion? I will discuss the development of the new method to estimate dust depletion, its application, and exciting results addressing the above questions. |
