Tutorial: Instanteous and Non Instantaneous Recycling - galacticusorg/galacticus GitHub Wiki

Galacticus tracks metals produced by stellar evolution. How this is done is controlled by the stellarPopulationProperties parameter which selects between different ways of computing properties of stellar populations.

Choosing stellarPopulationProperties=instantaneous will cause Galacticus to use the instantaneous recycling approximation for all calculations of stellar populations. The recycled fraction and metal yield are determined from the stellarPopulation provided by a stellarPopulationSelector.

Setting stellarPopulationProperties=noninstantaneous causes Galacticus to use a fully non-instantaneous, metal-depdendent calculation of recycling, metal production and rates. These rates are determined from the stellarPopulation provided by a stellarPopulationSelector. However, it is possible to force this method to operate in the instantaneous recycling approximation limit (which can be useful for testing and comparison) by setting:

      <stellarPopulations value="standard">
        <!-- Force the calculation of recycling, yields etc. to   -->
        <!-- be done assuming instantaneous recycling             -->
        <instantaneousRecyclingApproximation value="true"/>
        <!-- Set the recycled fraction and yield -->
        <recycledFraction value="0.35"/>
        <metalYield       value="0.02"/>
      </stellarPopulationProperties>

where the recycled fraction and metal yield are specified directly, or

      <stellarPopulations value="standard">
        <!-- Force the calculation of recycling, yields etc. to   -->
        <!-- be done assuming instantaneous recycling             -->
        <instantaneousRecyclingApproximation value="true"/>
        <!-- Set the mass of stars which should be used as the    -->
        <!-- dividing line between long-lived and instantaneously -->
        <!-- evolving in this approximation.                      -->
        <massLongLived value="1.0"/>
        <!-- Set the effective age of populations to use in this -->
        <!-- approximation when computing SNe numbers.           -->
        <ageEffective value="13.8"/>
      </stellarPopulationProperties>

in which case the recycled fraction and metal yield will be computed that all stars with mass greater than massLongLived have fully evolved, and energy input (from stellar winds and supernovae) will be computed assuming that stellar populations instantaneously reach an age of ageEffective.