.. _physics-radiativeTransferSpectrum:

Radiative Transfer Spectra
==========================

Class providing spectral energy distributions of sources for Monte Carlo radiative transfer calculations---the luminosity (in :math:`L_\odot` \AA\ :math:`^{-1}`) as a function of wavelength and the integrated luminosity over a wavelength range, used to initialize photon packet energies and to draw photon wavelengths from the source spectrum. Implementations include blackbody spectra, stellar population SEDs, and AGN power-law spectra, and determine the energy budget of photon packets launched into the computational domain.

**Default implementation:** ``radiativeTransferSpectrumBlackBody``

Methods
-------

``luminosity`` → ``double precision``
   Return the luminosity in the given wavelength range.

   * ``double precision, intent(in ) :: wavelengthMinimum, wavelengthMaximum``

``spectrum`` → ``double precision``
   Return the spectrum (in units of :math:`L_\odot` \AA\ :math:`^{-1}`) of the source at the given ``wavelength``.

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

.. _physics-radiativeTransferSpectrumAccretionDisk:

``radiativeTransferSpectrumAccretionDisk``
------------------------------------------

A photon spectrum class that computes the spectral luminosity of radiation emitted by an accreting black hole accretion disk in radiative transfer calculations. The black hole mass and Eddington-scaled accretion rate are set by the ``[blackHoleMass]`` and ``[accretionRateEddington]`` parameters.

**Parameters**

* ``[massBlackHole]`` (real; default ``1.0d6``) — The mass of the black hole at the center of the accretion disk.
* ``[accretionRateEddington]`` (real; default ``1.0d-1``) — Accretion rate onto the black hole in units of the Eddington rate.

.. _physics-radiativeTransferSpectrumBandPassFilter:

``radiativeTransferSpectrumBandPassFilter``
-------------------------------------------

A photon spectrum class that applies a wavelength band-pass filter to another photon spectrum, returning zero luminosity outside the specified wavelength range. The passband is controlled by the ``[wavelengthMinimum]`` and ``[wavelengthMaximum]`` parameters (in units of \AA).

**Parameters**

* ``[wavelengthMinimum]`` (real; default ``0.0d0``) — The minimum wavelength (in units of \AA) to pass the spectrum.
* ``[wavelengthMaximum]`` (real; default ``huge(0.0d0)``) — The maximum wavelength (in units of \AA) to pass the spectrum.

.. _physics-radiativeTransferSpectrumBlackBody:

``radiativeTransferSpectrumBlackBody``
--------------------------------------

A photon spectrum class that computes the spectral luminosity of a thermal blackbody source for use in radiative transfer calculations, scaling the Planck function to a specified bolometric luminosity. The blackbody temperature and total bolometric luminosity are set by the ``[temperature]`` (in Kelvin) and ``[luminosityBolometric]`` (in :math:`L_\odot`) parameters.

**(Default implementation)**

**Methods**

* ``temperature`` — Return the temperature of the black-body radiation field.

**Parameters**

* ``[temperature]`` (real; default ``5.0d3``) — The temperature (in Kelvin) of the blackbody radiation field, which sets the peak wavelength and total emitted flux via the Planck function.
* ``[luminosityBolometric]`` (real; default ``1.0d0``) — The bolometric luminosity of the black body spectrum (in :math:`L_\odot`).

.. _physics-radiativeTransferSpectrumPowerLaw:

``radiativeTransferSpectrumPowerLaw``
-------------------------------------

A photon spectrum class for power law spectra of the form

.. math::

   L_\lambda (\lambda) = \begin{array}{cc} A (\lambda/\lambda_\mathrm{min})^\alpha & \hbox{if } \lambda_\mathrm{min} \le \lambda < \lambda_\mathrm{max} \\ 0 & \hbox{otherwise,} \end{array}

where :math:`A=`\ ``normalization``, :math:`\alpha=`\ ``exponent``, :math:`\lambda_\mathrm{min}=`\ ``wavelengthMinimum``, and :math:`\lambda_\mathrm{max}=`\ ``wavelengthMaximum``.

**Parameters**

* ``[wavelengthMinimum]`` (real) — The minimum wavelength (in units of \AA) for the power-law spectrum.
* ``[wavelengthMaximum]`` (real) — The maximum wavelength (in units of \AA) for the power-law spectrum.
* ``[exponent]`` (real) — Parameter :math:`\gamma` appearing in model for random errors in the halo mass function. Specifically, the fractional error is given by :math:`\sigma(M) = \left[ \sigma^2_{12} \left({M_\mathrm{halo} \over 10^{12}\mathrm{M}_\odot}\right)^{2\gamma} + \sigma^2_\infty \right]^{1/2}`, where :math:`\sigma_{12}=`\ ``[normalization]`` and :math:`\gamma=`\ ``[exponent]``.
* ``[normalization]`` (real) — Parameter :math:`\sigma_{12}` appearing in model for random errors in the halo mass function.