+.. sectionauthor:: Britton Smith <firstname.lastname@example.org>
+This functionality provides the ability to create metallicity-dependent
+X-ray luminosity, emissivity, and photo emissivity fields for a given
+photon energy range. This works by interpolating from emission tables
+created with the photoionization code, `Cloudy <http://nublado.org/>`_.
+If you installed yt with the install script, the data should be located in
+the *data* directory inside the installation directory. Emission fields can
+be made for any interval between 0.1 keV and 100 keV.
+Fields can be created for luminosity (erg/s), emissivity (erg/s/cm^3),
+and photon emissivity (photons/s/cm^3). The only required arguments are
+the minimum and maximum energies.
+ from yt.analysis_modules.spectral_integrator.api import \
+ add_xray_luminosity_field, \
+ add_xray_emissivity_field, \
+ add_xray_luminosity_field(0.5, 7)
+ add_xray_emissivity_field(0.5, 7)
+ add_xray_photon_emissivity_field(0.5, 7)
+Additional keyword arguments are:
+ * **filename** (*string*): Path to data file containing emissivity
+ values. If None, a file called xray_emissivity.h5 is used. This file
+ contains emissivity tables for primordial elements and for metals at
+ solar metallicity for the energy range 0.1 to 100 keV. Default: None.
+ * **with_metals** (*bool*): If True, use the metallicity field to add the
+ contribution from metals. If False, only the emission from H/He is
+ considered. Default: True.
+ * **constant_metallicity** (*float*): If specified, assume a constant
+ metallicity for the emission from metals. The *with_metals* keyword
+ must be set to False to use this. Default: None.
+The resulting fields can be used like all normal fields.
+ pf = load("enzo_tiny_cosmology/DD0046/DD0046")
+ plot = SlicePlot(pf, 'x', 'Xray_Luminosity_0.5_7keV')
+ plot = ProjectionPlot(pf, 'x', 'Xray_Emissivity_0.5_7keV')
+ plot = ProjectionPlot(pf, 'x', 'Xray_Photon_Emissivity_0.5_7keV')