CosmicGrain: An On-the-fly Dust Physics Module

Abstract

We present CosmicGrain, a dust physics module built on Gadget-4 that models explicit dust superparticles that experience resolved gas-dust drag and radiation pressure, undergo collisional heating and cooling with gas, and are further shaped by subgrid treatments for grain growth, thermal sputtering, coagulation, shattering, supernova shock destruction, and astration. We run an eleven-rung physics ladder (S0-S10) at 1024^3 resolution to isolate the contribution of individual processes to a Milky Way-mass halo's dust population. Because dust is evolved as active on-the-fly particles, individual grains retain distinct histories producing results inaccessible to passive dust models such as the strongly asymmetric silicate-to-carbon shattering destruction ratio driven by silicate grains' smaller birth size. Gas-dust drag is the dominant driver of ISM dust enrichment, increasing dust levels by ~100 times while every other process changes the R200 dust abundance by only 10-30%. We find reasonable agreement with the Milky Way's radial dust-to-gas and dust-to-metal ratios, with carbon dust preferentially enriching the CGM relative to silicates. The code is freely available at https://cosmicgrain.space.