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.
>>> create_model_component("bbody", "mdl") >>> print(mdl)
Create a component of the bbody model and display its default parameters. The output is:
mdl Param Type Value Min Max Units ----- ---- ----- --- --- ----- mdl.space frozen 0 0 1 0 - energy | 1 - wave mdl.kT thawed 1 0.1 1000 keV mdl.ampl thawed 1 1e-20 1e+20
The attributes for this object are:
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.
The temperature if the blackbody, in keV.
The amplitude of the blackbody component.
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.
See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.