Radio non thermal emission

pcigale/creation_modules/synchrotron.py

+# -*- coding: utf-8 -*-
+# Copyright (C) 2013 Centre de données Astrophysiques de Marseille
+# Copyright (C) 2013 Institute of Astronomy, University of Cambridge
+# Licensed under the CeCILL-v2 licence - see Licence_CeCILL_V2-en.txt
+# Author: Médéric Boquien
+
+"""
+Radio module
+=============================
+
+This module implements the radio emission of galaxies, taking into account only the non-thermal emission.
+The thermal emission is handled by the nebular module.
+The parameters that this module takes as input are:
+- the value of the coefficient of the FIR/radio correlation
+- the value of the spectral index of the power law emission from synchrotron.
+
+"""
+
+import numpy as np
+import scipy.constants as cst
+from collections import OrderedDict
+from . import CreationModule
+
+
+class Radio(CreationModule):
+    """Radio emission
+
+    Given the number of Lyman photons, the module computes the free-free (thermal) emission of galaxies.
+    Based on the SN collapse rate, the module computes the synchrotron (non-thermal) emission of galaxies.
+
+    """
+
+    parameter_list = OrderedDict([
+        ("qir", (
+            "float",
+            "The value of the FIR/radio correlation coefficient.",
+            2.58
+        )),
+        ("alpha", (
+            "float",
+            "The slope of the power-law synchrotron emission.",
+            0.8
+        ))
+    ])
+
+    out_parameter_list = OrderedDict([
+        ("qir", "The value of the FIR/radio correlation coefficient."),
+        ("alpha", "The slope of the power-law synchrotron emission.")
+    ])
+
+    def _init_code(self):
+        """Build the model for a given set of parameters."""
+		
+        qir = float(self.parameters["qir"])
+        alpha = float(self.parameters["alpha"])
+
+        # We define various constants necessary to compute the model. For
+        # consistency, we define the speed of light in nm s¯¹ rather than in
+        # m s¯¹.
+        c = cst.c * 1e9
+        # We define the wavelength range for the non thermal emission
+        self.wave = np.logspace(5., 9., 1000.) 
+        # We compute the synchrotron emission normalised at 21cm       
+        self.lumin_nonthermal = (1./self.wave)**(-alpha + 2) / (1./2.1e8)**(-alpha + 2)
+        # Normalisation factor from the FIR/radio correlation to apply to the 
+        # IR luminosity
+        S21cm = (1./ (10**qir*3.75e12))*(c/(2.1e8)**2)
+        self.lumin_nonthermal *= S21cm
+
+        
+    def process(self, sed):
+        """Add the radio contribution.
+
+        Parameters
+        ----------
+        sed: pcigale.sed.SED object
+
+        """
+        if 'dust.luminosity' not in sed.info.keys():
+            sed.add_info('dust.luminosity', 1., True)
+        luminosity = sed.info['dust.luminosity']
+
+        sed.add_module(self.name, self.parameters)
+        sed.add_info("radio.qir", self.parameters["qir"])
+        sed.add_info("radio.alpha", self.parameters["alpha"])
+        sed.add_contribution('radio_nonthermal', self.wave,   self.lumin_nonthermal * luminosity)
+
+# CreationModule to be returned by get_module
+Module = Radio