SAGE26 Documentation

SAGE26 is a C99 semi-analytic code for modelling galaxy formation in a cosmological context, extending Croton et al. (2016) with a two-regime CGM model, FIRE stellar feedback, feedback-free burst (FFB) galaxies, and extended bulge/ICS tracking.

Source code and issue tracker: https://github.com/MBradley1985/SAGE26

User Guide

• Getting Started
  • Dependencies
  • Build
  • First run
  • Running the model
  • Plotting
  • Tests
• SAGE26 Parameter Reference
  • Output
  • Simulation
  • Units
  • Physics switches
  • FFB parameters
  • H₂ star formation parameters
  • Model parameters
  • Numerical time resolution
  • MPI forest distribution
  • Removed parameters
• Outputs
  • Output formats
  • HDF5 layout
  • Binary layout
  • Flag conventions
  • Galaxy property reference
  • Cumulative star formation history (SaveFullSFH = 1)
  • Binary vs HDF5 name differences
  • Parameter -> output mapping
  • Where to go next

Physics

• Per-Halo Physics Loop
  • In one paragraph
  • Sub-stepping
  • Order of operations
  • Post-step bookkeeping
  • The two-regime split as a code path map
  • Galaxy types
  • Reading the source
  • Where to go next
• Units and Conventions
  • Code units
  • h-factor conventions
  • Departures from code units
  • Frozen single-precision sites
  • Naming convention
• Infall, Reincorporation, and Stripping
  • What infall represents
  • infall_recipe() – the per-snapshot budget
  • Reionization suppression – do_reionization()
  • add_infall_to_hot() – per-substep injection
  • reincorporate_gas() – ejected mass returning to hot
  • strip_from_satellite() – satellite hot-gas stripping
  • Switches and parameters
  • References
• Cooling and AGN Heating
  • The two cooling regimes
  • Dispatcher – cooling_recipe_regime_aware()
  • cooling_recipe_hot() – Regime 1 (classical hot halo)
  • cooling_recipe_cgm() – Regime 0 (Carr et al. 2023 bulk cooling)
  • AGN radio-mode heating
  • cool_gas_onto_galaxy()
  • Switches and parameters
  • References
• Star Formation and Feedback
  • Per-substep orchestration – starformation_and_feedback()
  • Star formation prescriptions
  • Supernova feedback
  • update_from_star_formation() and update_from_feedback()
  • Metal production and routing
  • Feedback-free burst mode – starformation_ffb()
  • What is NOT in this module
  • Switches and parameters
  • References
• Disk Instability
  • What disk instability does
  • Splitting the unstable mass
  • Where the unstable stars go
  • Where the unstable gas goes
  • Order of operations and bookkeeping
  • What is NOT in this module
  • Switches and parameters
  • References
• Disk sizes
  • What the published expression is
  • How sensitive the model is
  • Where it disagrees with the size data
  • Halo spin is resolution-biased
  • What each level does
  • What level 2 does not fix: the HI mass function
  • The excess is a bimodal tail, not a mass window
  • The disc radius is the root cause – via instability, not surface density
  • What is deliberately unchanged
• Mergers and Disruption
  • When this step fires
  • deal_with_galaxy_merger() – the merger dispatcher
  • Quasar-mode AGN – grow_black_hole()
  • collisional_starburst_recipe() – the merger starburst
  • The two-channel bulge model
  • Satellite disruption – disrupt_satellite_to_ICS()
  • What is NOT in this module
  • Switches and parameters
  • References
• Intracluster Stars (ICS)
  • Fields
  • How ICS forms
  • How to compute the mean ICS assembly time
  • ICS in the baryon budget
  • Type-0 vs satellite ICS
  • Switches and parameters
  • References

API Reference

• C API Reference
  • Physics
  • Core

Project

• Changelog
• Contributing to SAGE26