.. _physics-stellarPopulationSpectraPostprocessor:

Postprocessors for stellar population spectra
=============================================

Class providing postprocessors for stellar population spectra---multiplicative corrections to the spectral energy distribution applied after the intrinsic stellar population spectrum is computed. Each postprocessor returns a wavelength-, age-, and redshift-dependent multiplicative factor to account for effects such as :term:`IGM` absorption of Lyman-series photons, intergalactic dust attenuation, or other propagation effects between the source and the observer. Multiple postprocessors can be chained to apply cumulative corrections for different physical processes.

**Default implementation:** ``stellarPopulationSpectraPostprocessorInoue2014``

Methods
-------

``multiplier`` → ``double precision``
   Return the multiplicative correction factor (between 0 and 1) to apply to the stellar population spectrum at the given wavelength (\AA), stellar population age (Gyr), and source redshift, accounting for propagation effects such as IGM absorption.

   * ``double precision, intent(in ) :: wavelength, age, redshift``

``isRedshiftDependent`` → ``logical``
   Return true if this postprocessor's correction factor depends on the source redshift, allowing the ODE solver to determine whether the luminosity must be recomputed when the redshift changes rather than using a cached value.

.. _physics-stellarPopulationSpectraPostprocessorAgeWindow:

``stellarPopulationSpectraPostprocessorAgeWindow``
--------------------------------------------------

A stellar population postprocessor class which keeps only emission from populations with ages between ``[ageMinimum]`` and ``[ageMaximum]``.

**Parameters**

* ``[ageMinimum]`` (default ``0.0d0``) — The minimum stellar population age (in Gyr) to retain in the age-window postprocessor; populations younger than this threshold contribute zero luminosity, effectively excluding very young stars from the integrated spectrum.
* ``[ageMaximum]`` (default ``huge(0.0d0)``) — The maximum stellar population age (in Gyr) to retain in the age-window postprocessor; populations older than this threshold contribute zero luminosity, effectively excluding old stellar populations from the integrated spectrum.

.. _physics-stellarPopulationSpectraPostprocessorBirthCloudsLacey2016:

``stellarPopulationSpectraPostprocessorBirthCloudsLacey2016``
-------------------------------------------------------------

Retains only only populations which remain in their birth clouds according to the model of :cite:t:`lacey_unified_2016`.

**Parameters**

* ``[timescale]`` (default ``1.0d-3``) — The timescale for "escape" of stellar populations from their birth clouds.

.. _physics-stellarPopulationSpectraPostprocessorIdentity:

``stellarPopulationSpectraPostprocessorIdentity``
-------------------------------------------------

A stellar population postprocessing class which leaves the spectrum unchanged.

**Parameters**

* ``[redshift]`` (default ``0.0d0``) — The redshift at which the transfer function is defined.

.. _physics-stellarPopulationSpectraPostprocessorInoue2014:

``stellarPopulationSpectraPostprocessorInoue2014``
--------------------------------------------------

A stellar population postprocessing class that postprocesses spectra through absorption by the :term:`IGM` using the results of :cite:t:`inoue_updated_2014`.

**(Default implementation)**

.. _physics-stellarPopulationSpectraPostprocessorLycSuppress:

``stellarPopulationSpectraPostprocessorLycSuppress``
----------------------------------------------------

A stellar population spectrum postprocessor class that suppresses all emission in the Lyman continuum.

.. _physics-stellarPopulationSpectraPostprocessorMadau1995:

``stellarPopulationSpectraPostprocessorMadau1995``
--------------------------------------------------

A stellar population postprocessor class that postprocesses spectra through absorption by the :term:`IGM` using the results of :cite:t:`madau_radiative_1995`.

.. _physics-stellarPopulationSpectraPostprocessorMeiksin2006:

``stellarPopulationSpectraPostprocessorMeiksin2006``
----------------------------------------------------

A stellar population postprocessor class that postprocesses spectra through absorption by the :term:`IGM` using the results of :cite:t:`meiksin_colour_2006`.

.. _physics-stellarPopulationSpectraPostprocessorRecent:

``stellarPopulationSpectraPostprocessorRecent``
-----------------------------------------------

A stellar population postprocessor class which suppresses all emission from populations older than ``[timeLimit]`` (in Gyr).

**Parameters**

* ``[timeLimit]`` (default ``1.0d-2``) — The maximum age of stellar populations to retain in the "recent" spectra postprocessing method.
* ``[timeRecent]`` — The parameter :math:`\Delta t` (in units of Gyr) appearing in the recent node major merger galactic filter class.

.. _physics-stellarPopulationSpectraPostprocessorSequence:

``stellarPopulationSpectraPostprocessorSequence``
-------------------------------------------------

A stellar population spectra postprocessor class that applies a sequence of other postprocessors in order, computing the total multiplicative correction as the product of all individual postprocessor multipliers, allowing multiple physical effects (e.g., IGM absorption and dust) to be combined.

**Methods**

* ``prepend`` — Prepend an operator to a sequence of weight operators.

.. _physics-stellarPopulationSpectraPostprocessorUnescaped:

``stellarPopulationSpectraPostprocessorUnescaped``
--------------------------------------------------

A stellar population spectra postprocessor that retains only the emission from stellar populations that have not yet escaped their birth environment (i.e., those younger than a specified timescale), suppressing the contribution of stars older than the escape timescale.

**Parameters**

* ``[timescale]`` (default ``1.0d-2``) — The timescale for "escape" of stellar populations in the "unescaped" spectra postprocessing method.