Commit b7e1269e authored by Matthieu Schaller's avatar Matthieu Schaller
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Description of the YAML parameters for the EAGLE cooling in the RTD.

parent 9af1c5e2
......@@ -104,11 +104,12 @@ an absolute metal mass (say) for a star, the ``InitialMass`` (see
below) of the star must be used.
The chemistry model only requires a small number of parameters to be
specified in the YAML file. These are the initial values of the
metallicity and element mass fractions. These are then applied at the
start of a simulation to *all* the *gas* particles. All 9 elements have
to be specified An example section, for primordial abundances (typical
for a cosmological run), is:
specified in the `EAGLEChemistry` section of the YAML file. These are
the initial values of the metallicity and element mass
fractions. These are then applied at the start of a simulation to
*all* the *gas* particles. All 9 elements have to be specified An
example section, for primordial abundances (typical for a cosmological
run), is:
.. code:: YAML
......@@ -166,19 +167,24 @@ element abundance relative to the solar abundance pattern assumed by the tables
(see equation 4 in the original paper). As the particles do not carry the mass
fraction of `S` and `Ca`, we compute the contribution to the cooling rate of
these elements from the abundance of `Si`. More specifically, we assume that
their abundance relative to the table's solar abundance pattern is the same as
the relative abundance of `Si`. Users can optionally modify the ratios used for
`S` and `Ca`.
their abundance by mass relative to the table's solar abundance pattern is the
same as the relative abundance of `Si` (i.e. :math:`[Ca/Si] = 0` and
:math:`[S/Si] = 0`). Users can optionally modify the ratios used for `S` and
`Ca`.
Above the redshift of Hydrogen re-ionization we use the extra table containing
net cooling rates for gas exposed to the CMB and a UV + X-ray background at
redshift nine truncated above 1 Rydberg. At the redshift or re-ionization, we
additionally inject a fixed user-defined amount of energy per unit mass.
additionally inject a fixed user-defined amount of energy per unit mass to all
the gas particles.
In addition to the tables we inject extra energy from Helium re-ionization using
a Gaussian model with a user-defined redshift for the centre, width and total
amount of energy injected per unit mass.
For non-cosmological run, we use the :math:`z = 0` table and the interpolation
along the redshift dimension then becomes a trivial operation.
The cooling itself is performed using an implicit scheme (see the theory
documents) which for small values of the cooling rates is solved explicitly. For
larger values we use a bisection scheme. Users can alternatively use a
......@@ -193,6 +199,32 @@ We note that the EAGLE cooling model does not impose any restriction on the
particles' individual time-steps. The cooling takes place over the time span
given by the other conditions (e.g the Courant condition).
The cooling model is driven by a small number of parameter files in the
`EAGLECooling` section of the YAML file. These are the re-ionization parameters,
the path to the tables and optionally the modified abundances of `Ca` and `S` as
well as the flag to attempt using the Newton-Raphson scheme to solve the
implicit problem. A valid section of the YAML file looks like:
.. code:: YAML
EAGLECooling:
dirname: /path/to/the/Wiersma/tables/directory # Absolute or relative path
H_reion_z: 11.5 # Redhift of Hydrogen re-ionization
He_reion_z_centre: 3.5 # Centre of the Gaussian used for Helium re-ionization
He_reion_z_sigma: 0.5 # Width of the Gaussian used for Helium re-ionization
He_reion_ev_pH: 2.0 # Energy injected in eV per Hydrogen atom for Helium re-ionization.
The optional parameters are:
.. code:: YAML
EAGLECooling:
CalciumOverSiliconInSolar: 1.0 # (Optional) Value of the Calcium abundance ratio to solar in units of the Silicon ratio to solar. Default value: 1.
SulphurOverSiliconInSolar: 1.0 # (Optional) Value of the Sulphur abundance ratio to solar in units of the Silicon ratio to solar. Default value: 1.
newton_integration: 0 # (Optional) Set to 1 to use the Newton-Raphson scheme for the explicit cooling problem.
Particle tracers
~~~~~~~~~~~~~~~~
......
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