def __init__(self, N=0.0, b=10.0, D_fraction=1.5e-5): fuf.OneDFit.__init__(self, ["N","b", "Dfrac"], rootName="LyaTransmission") self["b"] = b self["Dfrac"] = D_fraction # (Only) Einstein coefficient relevant for LyA elya = 6.258085e8 # Hydrogen self._absH = VoigtAstroP() self._absH["w0"] = 1215.67 self._absH["b"] = self["b"] self._absH["gamma"] = convertDampingConstant(elya, 1215.67) self._absH["f"] = 0.416 # Deuterium, its width is sqrt(2) times smaller self._absD = VoigtAstroP() self._absD["w0"] = 1215.34 self._absD["b"] = self["b"]/np.sqrt(2.0) self._absD["gamma"] = convertDampingConstant(elya, 1215.67) self._absD["f"] = 0.416
class LyaTransmission(fuf.OneDFit):
"""
Lyman alpha transmission profile including Deuterium absorption.
The transmission is given by
.. math::
e^{-\\sigma N}\\, ,
where N is the column density and :math:`\\sigma` is the wavelength-dependent
cross-section.
*Fit Parameters*:
===== ============================= =====
N Hydrogen column density /cm^2
b Doppler parameter km/s
Dfrac Deuterium fraction --
===== ============================= =====
Parameters
----------
N : float, optional
Hydrogen column density [/cm^2]. The default is 0.
b : float, optional
The Doppler parameter (corresponds to sqrt(2) times
the velocity dispersion) to model thermal line width [km/s].
The default is 10 km/s.
D_fraction : float, optional
Fractional abundance of Deuterium with respect to Hydrogen.
The default is 1.5e-5.
"""
def __init__(self, N=0.0, b=10.0, D_fraction=1.5e-5):
fuf.OneDFit.__init__(self, ["N","b", "Dfrac"], rootName="LyaTransmission")
self["b"] = b
self["Dfrac"] = D_fraction
# (Only) Einstein coefficient relevant for LyA
elya = 6.258085e8
# Hydrogen
self._absH = VoigtAstroP()
self._absH["w0"] = 1215.67
self._absH["b"] = self["b"]
self._absH["gamma"] = convertDampingConstant(elya, 1215.67)
self._absH["f"] = 0.416
# Deuterium, its width is sqrt(2) times smaller
self._absD = VoigtAstroP()
self._absD["w0"] = 1215.34
self._absD["b"] = self["b"]/np.sqrt(2.0)
self._absD["gamma"] = convertDampingConstant(elya, 1215.67)
self._absD["f"] = 0.416
def evaluate(self, x):
"""
Evaluate the transmission profile.
Parameters
----------
x : array of floats
Contains the wavelength values in Angstrom.
Returns
-------
Model : array of floats
The line profile.
"""
self._absH["b"] = self["b"]
self._absD["b"] = self["b"]/np.sqrt(2.0)
y = np.exp(-self["N"] * self._absH.evaluate(x)) * \
np.exp(-self["N"] * self["Dfrac"] * self._absD.evaluate(x))
return y
