CosmicGrain¶
Dust evolution for GADGET-4 cosmological simulations.
CosmicGrain is an open-source dust simulation code built on GADGET-4. Individual grain populations are represented by explicit PartType6 superparticles that carry their own dynamics, size, composition, and stellar origin while evolving through creation, transport, growth, collisions, and destruction.
CosmicGrain is distributed as a complete GADGET-4-based simulation code rather than a standalone plug-in. It can be used to run the included dust model, explore alternative dust prescriptions and parameters, or serve as a foundation for new dust-physics implementations.
Why evolve the grains explicitly?¶
Treating dust as a dynamical particle population allows the grain distribution to respond to both its local physical environment and its history. Stellar sources seed grains with different characteristic sizes and compositions; drag transports them relative to the gas; growth, coagulation, and shattering reshape the size distribution; and sputtering, shocks, and astration remove material.
The resulting particle population can be analyzed directly in terms of grain size, composition, and provenance, or connected to observables such as dust-to-gas ratios, extinction curves, and spatially varying \(R(V)\).
Using CosmicGrain¶
Run¶
Use the complete CosmicGrain model for cosmological or galaxy simulations with explicit dust evolution.
Experiment¶
Change source yields, grain sizes, processing efficiencies, destruction prescriptions, and other dust parameters.
Extend¶
Use the existing dust-particle and GADGET-4 coupling infrastructure as a foundation for implementing new dust physics.
Documentation map¶
- Getting Started — obtain the complete source, compile it, and run a first simulation
- Running CosmicGrain — parameters, initial conditions, outputs, restarts, and performance
- Dust Physics — the physical prescriptions implemented in the current model
- Analysis — particle fields, grain populations, composition, extinction, maps, and synthetic observations
- Validation — numerical integrity, resolution sensitivity, and convergence limitations
- Developer Guide — current architecture and guidance for modifying or adding dust physics
- Reference — compile flags, runtime parameters, particle types, and units
Current science program¶
The current zoom suite contains 12 halos spanning dwarf through super-Milky-Way masses, with multiple resolution levels used for validation and convergence work. Lower-resolution calculations are treated as numerical validation where appropriate rather than automatically as converged galaxy predictions.
The public documentation distinguishes implemented physics, current calibration choices, and numerical/scientific validation. Parameters used for a particular production suite should therefore be archived with that run rather than assumed to be universal CosmicGrain defaults.