Pop III and Star Cluster Formation/Feedback Updates

#293 Merged at d99a67e
  1. John Wise

This PR has many changes to the Population III star formation and radiating star cluster formation routines, methods 3 and 5, respectively. It does not affect other star formation routines.

  • New feature: Option to write an interpolated output just after Pop III star formation or a supernova. Parameter PopIIIOutputOnFeedback.

  • New feature: Adding a timestep limiter based on cooling time. New parameters: UseCoolingTimestep, CoolingTimestepSafetyFactor (default = 0.1). Note: Accidentally duplicated in the chem_energy_changes PR when categorizing changes. I had transplated it from Britton Smith's fork twice.

  • New feature: Added new parameters to halt the simulation when a metal-enriched gas reaches some density. Controlled by parameters, StopFirstTimeAtMetalEnrichedDensity, specified in units of g/cm^3, and EnrichedMetalFraction, specified in absolute metal fraction (default = 1e-8).

  • New feature: Added core-collapse supernova models for Pop III stars, using the ejecta mass from Nomoto et al (2006) and a mass-independent 1e51 erg explosion energy. Triggered by PopIIIUseHypernovae == FALSE.

  • New feature: Added new parameter, PopIIISupernovaExplosions, which can completely turn off Pop III supernovae. Default == TRUE.

  • Improvement: Changes to the mass removal after star formation: The surrounding region is still assumed to be ionized and heated as the initial Stroemgren sphere forms. To avoid artifical cooling before the central source radiates, a 1/r^2 photo-heating and photo-ionizing rates are injected into the sphere.

  • Improvement: Changes to the supernovae energy injection: Species fractions are now located initialized as ionized. The chem/energy solver will take care of this at high temperatures. Metals are now added evenly throughout the sphere; before, the gas was forced to have a uniform metallicity.

  • Improvement: Optimizations to the routines that determine the overlapping grids with a feedback sphere.

  • Model change: Changed time for a Pop III stellar radiation to increase to its ZAMS luminosity from 50 kyr to 10 kyr (Susa 2014).

  • Solver change: Increasing maximum chem/energy iteration to 100k.

  • Code change: Put the H2 dissociation radiation calculation from point sources into its own routine.

  • BUGFIX: Corrected a bug that removed gas from the wrong cell after BH accretion.

  • BUGFIX: Corrected a bug that incorrectly calculated the SN feedback sphere's radius incorrectly when r < dx.

Comments (10)

      1. Brian O'Shea

        Following up on this PR: we still desperately need a third person -- preferably somebody who has some familiarity with this code -- to take a quick look over it!

  1. Greg Bryan

    I just looked it over and it seems good to me! I had two minor comments, but they are just related to presentation and John can either fix or ignore.