BBody¶
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class
sherpa.astro.models.
BBody
(name='bbody')[source] [edit on github]¶ Bases:
sherpa.models.model.RegriddableModel1D
A one-dimensional Blackbody model.
A model representing the ideal blackbody function. It can be used when the independent axis is in energy or wavelength space.
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space
¶ Switch to select whether the independent axis is energy or wavelength. This parameter is not fit (
alwaysfrozen
is set), and should be set to either 0, when the independent axis is energy with units of keV, or 1 when the axis is wavelength with units of Angstrom.
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kT
¶ The temperature if the blackbody, in keV.
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ampl
¶ The amplitude of the blackbody component.
See also
Notes
The blackbody emission is calculated as a function of energy using the expression:
f(E) = ampl * E^2 / (exp(E / kT) - 1)
where E is the photon energy, and kT is the blackbody temperature (both in keV). The amplitude, ampl, is related to the ratio of source radius to distance by:
ampl = (2 * pi / (c^2 * h^3)) (R / d)^2 = 9.884 x 10^31 (R / d)^2
with Planck’s constant (h) specified in keV-s and the speed of light (c) specified in cm/s, and with R and d representing the radius of, and distance to, the source respectively.
There are two conditions when the above equation is not used:
- if E/kt < 10^-4 then f(E) = ampl * E * kT
- if E/kT > 60, f(E) = 0.
Attributes Summary
thawedparhardmaxes
thawedparhardmins
thawedparmaxes
thawedparmins
thawedpars
Methods Summary
apply
(outer, *otherargs, **otherkwargs)calc
(pars, xlo, *args, **kwargs)get_center
()guess
(dep, *args, **kwargs)Set an initial guess for the parameter values. regrid
(*arrays)reset
()set_center
(*args, **kwargs)startup
()Called before a model may be evaluated multiple times. teardown
()Called after a model may be evaluated multiple times. Attributes Documentation
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thawedparhardmaxes
¶
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thawedparhardmins
¶
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thawedparmaxes
¶
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thawedparmins
¶
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thawedpars
¶
Methods Documentation
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apply
(outer, *otherargs, **otherkwargs) [edit on github]¶
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calc
(pars, xlo, *args, **kwargs) [edit on github]¶
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get_center
() [edit on github]¶
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guess
(dep, *args, **kwargs)[source] [edit on github]¶ Set an initial guess for the parameter values.
Attempt to set the parameter values, and ranges, for the model to match the data values. This is intended as a rough guess, so it is expected that the model is only evaluated a small number of times, if at all.
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regrid
(*arrays) [edit on github]¶
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reset
() [edit on github]¶
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set_center
(*args, **kwargs) [edit on github]¶
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startup
() [edit on github]¶ Called before a model may be evaluated multiple times.
See also
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teardown
() [edit on github]¶ Called after a model may be evaluated multiple times.
See also
setup()
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