.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        Click :ref:`here <sphx_glr_download_modeling_gallery_spectral_plot_absorbed.py>`     to download the full example code
    .. rst-class:: sphx-glr-example-title

    .. _sphx_glr_modeling_gallery_spectral_plot_absorbed.py:


.. _absorbed-spectral-model:

Absorbed Spectral Model
=======================

This model evaluates absorbed spectral model.

The spectral model is evaluated, and then multiplied with an EBL
absorption factor given by

.. math::
    \exp{ \left ( -\alpha \times \tau(E, z) \right )}

where :math:`\tau(E, z)` is the optical depth predicted by the model
(`~gammapy.modeling.models.Absorption`), which depends on the energy of the gamma-rays and the
redshift z of the source, and :math:`\alpha` is a scale factor
(default: 1) for the optical depth.

Example plot
------------
Here is an example plot of the model:


.. code-block:: default


    from astropy import units as u
    import matplotlib.pyplot as plt
    from gammapy.modeling.models import (
        AbsorbedSpectralModel,
        Absorption,
        Models,
        PowerLawSpectralModel,
        SkyModel,
    )

    redshift = 0.117
    absorption = Absorption.read_builtin("dominguez")

    # Spectral model corresponding to PKS 2155-304 (quiescent state)
    index = 3.53
    amplitude = 1.81 * 1e-12 * u.Unit("cm-2 s-1 TeV-1")
    reference = 1 * u.TeV
    pwl = PowerLawSpectralModel(index=index, amplitude=amplitude, reference=reference)

    # EBL + PWL model
    model = AbsorbedSpectralModel(
        spectral_model=pwl, absorption=absorption, redshift=redshift
    )

    energy_range = [0.1, 100] * u.TeV
    model.plot(energy_range)
    plt.grid(which="both")
    plt.ylim(1e-24, 1e-8)




.. image:: /modeling/gallery/spectral/images/sphx_glr_plot_absorbed_001.png
    :class: sphx-glr-single-img





YAML representation
-------------------
Here is an example YAML file using the model:


.. code-block:: default


    model = SkyModel(spectral_model=model, name="absorbed-model")
    models = Models([model])

    print(models.to_yaml())




.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    components:
    -   name: absorbed-model
        type: SkyModel
        spectral:
            type: AbsorbedSpectralModel
            base_model:
                type: PowerLawSpectralModel
                parameters:
                - {name: index, value: 3.53, unit: '', min: .nan, max: .nan, frozen: false,
                    error: 0}
                - {name: amplitude, value: 1.81e-12, unit: cm-2 s-1 TeV-1, min: .nan,
                    max: .nan, frozen: false, error: 0}
                - {name: reference, value: 1.0, unit: TeV, min: .nan, max: .nan, frozen: true,
                    error: 0}
            absorption:
                type: Absorption
                filename: !!python/object/apply:pathlib.PosixPath [/, Users, terrier,
                    Code, gammapy-dev, gammapy-datasets, ebl, ebl_dominguez11.fits.gz]
            absorption_parameter: {name: redshift, value: 0.117}
            parameters:
            - {name: redshift, value: 0.117, unit: '', min: 0.009999999776482582, max: 3.990000009536743,
                frozen: true, error: 0}
            - {name: alpha_norm, value: 1.0, unit: '', min: .nan, max: .nan, frozen: true,
                error: 0}






.. _sphx_glr_download_modeling_gallery_spectral_plot_absorbed.py:


.. only :: html

 .. container:: sphx-glr-footer
    :class: sphx-glr-footer-example



  .. container:: sphx-glr-download sphx-glr-download-python

     :download:`Download Python source code: plot_absorbed.py <plot_absorbed.py>`



  .. container:: sphx-glr-download sphx-glr-download-jupyter

     :download:`Download Jupyter notebook: plot_absorbed.ipynb <plot_absorbed.ipynb>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_