BBody

class sherpa.astro.models.BBody(name='bbody')

Bases: sherpa.models.model.ArithmeticModel

A one-dimensional Blackbody model.

This model can be used when the independent axis is in energy or wavelength space.

space

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

BBodyFreq

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)
reset()
set_center(\*args, \*\*kwargs)
startup()
teardown()

Attributes Documentation

thawedparhardmaxes

thawedparhardmins

thawedparmaxes

thawedparmins

thawedpars

Methods Documentation

apply(outer, *otherargs, **otherkwargs)

calc(pars, xlo, *args, **kwargs)

get_center()

guess(dep, *args, **kwargs)

reset()

set_center(*args, **kwargs)

startup()

teardown()