BBody¶
- 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.
- 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.
- kT¶
The temperature if the blackbody, in keV.
- 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
The maximum size of the cache.
A one-dimensional model.
The hard maximum values for the thawed parameters.
The hard minimum values for the thawed parameters.
Access to the maximum limits for the thawed parameters
Access to the minimum limits for the thawed parameters
Access to the thawed parameters of the model
Methods Summary
apply
(outer, *otherargs, **otherkwargs)Clear the cache.
Display the cache status.
calc
(*args, **kwargs)Evaluate the model on a grid.
guess
(dep, *args, **kwargs)Set an initial guess for the parameter values.
regrid
(*args, **kwargs)The class RegriddableModel1D allows the user to evaluate in the requested space then interpolate onto the data space.
reset
()Reset the parameter values.
set_center
(*args, **kwargs)startup
([cache])Called before a model may be evaluated multiple times.
teardown
()Called after a model may be evaluated multiple times.
Attributes Documentation
- cache = 5¶
The maximum size of the cache.
- ndim = 1¶
A one-dimensional model.
- thawedparhardmaxes¶
The hard maximum values for the thawed parameters.
- thawedparhardmins¶
The hard minimum values for the thawed parameters.
- thawedparmaxes¶
Access to the maximum limits for the thawed parameters
- thawedparmins¶
Access to the minimum limits for the thawed parameters
- thawedpars¶
Access to the thawed parameters of the model
Methods Documentation
- apply(outer, *otherargs, **otherkwargs) [edit on github]¶
- cache_clear() [edit on github]¶
Clear the cache.
- cache_status() [edit on github]¶
Display the cache status.
Information on the cache - the number of “hits”, “misses”, and “requests” - is displayed at the INFO logging level.
Example
>>> pl.cache_status() powlaw1d.pl size: 5 hits: 633 misses: 240 check= 873
- calc(*args, **kwargs)[source] [edit on github]¶
Evaluate the model on a grid.
- Parameters
p (sequence of numbers) – The parameter values to use. The order matches the
pars
field.*args – The model grid. The values can be scalar or arrays, and the number depends on the dimensionality of the model and whether it is being evaluated over an integrated grid or at a point (or points).
- get_center() [edit on github]¶
- 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.
- regrid(*args, **kwargs) [edit on github]¶
The class RegriddableModel1D allows the user to evaluate in the requested space then interpolate onto the data space. An optional argument ‘interp’ enables the user to change the interpolation method.
Examples
>>> import numpy as np >>> from sherpa.models.basic import Box1D >>> mybox = Box1D() >>> request_space = np.arange(1, 10, 0.1) >>> regrid_model = mybox.regrid(request_space, interp=linear_interp)
- reset() [edit on github]¶
Reset the parameter values.
- set_center(*args, **kwargs) [edit on github]¶
- startup(cache=False) [edit on github]¶
Called before a model may be evaluated multiple times.
- Parameters
cache (bool, optional) – Should a cache be used when evaluating the models.
See also
- teardown() [edit on github]¶
Called after a model may be evaluated multiple times.
See also