.. _physics-intergalacticMediumFilteringMass:

Intergalactic Medium Filtering Mass
===================================

Class providing models of the :term:`IGM` filtering mass---the characteristic halo mass scale below which photo-ionization heating of the :term:`IGM` suppresses gas accretion. Photo-ionization by the UV background raises the :term:`IGM` temperature to :math:`\sim 10^4` K, increasing the Jeans mass and preventing low-mass halos from accreting their full cosmic baryon fraction. Implementations return the filtering mass :math:`M_\mathrm{F}(t)` (and its rate of change), and the suppressed baryon fraction :math:`f_\mathrm{b}(M,t)` relative to the cosmic mean, governing star formation in dwarf galaxies.

**Default implementation:** ``intergalacticMediumFilteringMassGnedin2000``

Methods
-------

``massFiltering`` → ``double precision``
   Return the filtering mass at the given ``time``.

   * ``double precision, intent(in ) :: time``

``massFilteringRateOfChange`` → ``double precision``
   Return the rate of change of the filtering mass at the given ``time``.

   * ``double precision, intent(in ) :: time``

``fractionBaryons`` → ``double precision``
   Return the fraction of baryons accreted into a halo of the given ``mass`` at the ``time``.

   * ``double precision, intent(in ) :: mass, time``

``fractionBaryonsGradientMass`` → ``double precision``
   Return the gradient with respect to mass of the fraction of baryons accreted into a halo of the given ``mass`` at the ``time``.

   * ``double precision, intent(in ) :: mass, time``

``fractionBaryonsRateOfChange`` → ``double precision``
   Return the rate of change of the fraction of baryons accreted into a halo of the given ``mass`` at the ``time``.

   * ``double precision, intent(in ) :: mass, time``

.. _physics-intergalacticMediumFilteringMassGnedin2000:

``intergalacticMediumFilteringMassGnedin2000``
----------------------------------------------

An implementation of the :cite:t:`gnedin_effect_2000` filtering mass calculation, which determines the characteristic halo mass below which gas accretion is suppressed by photoionization heating from the intergalactic radiation field. The filtering mass is computed by integrating an ODE system driven by the :term:`IGM` thermal state and linear growth history.

**(Default implementation)**

**Methods**

* ``tabulate`` — Tabulate the filtering mass to encompass at least the given ``time``.
* ``conditionsInitialODEs`` — Set the initial conditions for the ODE system.
* ``coefficientsEarlyEpoch`` — Return coefficients for the early-epoch fitting function to the filtering mass.
* ``massFilteringEarlyEpoch`` — Return the early-epoch solution for the filtering mass.
* ``fileWrite`` — Store the tabulate filtering mass to file.
* ``fileRead`` — Restore the tabulate filtering mass from file.
* ``remakeTable`` — Return true if the table must be remade.

**Parameters**

* ``[timeTooEarlyIsFatal]`` (default ``.true.``) — If true, requesting the filtering mass at a time earlier than the initial time provided by the :cite:t:`naoz_growth_2005` fit will result in a fatal error. Otherwise, the filtering mass is fixed at this initial value for earlier times.