Last modified: December 2023

AHELP for CIAO 4.16 Sherpa


Context: models


The XSPEC grbcomp model: Comptonization for GRB prompt emission.



The xsgrbcomp model is an additive model component.


The model is described at [1] .


>>> create_model_component("xsgrbcomp", "mdl")
>>> print(mdl)

Create a component of the xsgrbcomp model and display its default parameters. The output is:

   Param        Type          Value          Min          Max      Units
   -----        ----          -----          ---          ---      -----
   mdl.kTs      thawed            1            0           20        keV
   mdl.gamma    thawed            3            0           10           
   mdl.kTe      thawed          100          0.2         2000        keV
   mdl.tau      thawed            5            0          200           
   mdl.beta     thawed          0.2            0            1           
   mdl.fbflag   frozen            0            0            1           
   mdl.log_A    frozen            5           -8            8           
   mdl.z        frozen            0            0           10           
   mdl.a_boost  frozen            5            0           30           
   mdl.norm     thawed            1            0        1e+24           


The attributes for this object are:

Attribute Definition
kTs Temperature of the seed blackbody spectrum in keV.
gamma If set to 3 the seed soft spectrum is a blackbody, otherwise it approximates a modified blackbody.
kTe Electron temperature of the subrelativistic outflow in keV.
tau Radial optical depth of the subrelativistic outflow.
beta Bulk outflow velocity of the thermal electrons.
fbflag If set to 0 then only the first-order bulk Comptonization term is considered, otherwise if set to 1 then the second-order term is computed (see [1] for more details).
log_A The geometrical covering factor which determines the relative weights of the seed and comptonized spectra to the total flux.
z Redshift.
a_boost The energy index of the Green's function with which the formerly comptonization spectrum is convolved.
norm The normalization of the model: see [1] for an explanation of the units.


XSPEC version

CIAO 4.16 comes with support for version 12.13.1e of the XSPEC models. This can be checked with the following:

% python -c 'from sherpa.astro import xspec;


See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

xsgrbjet, xsgrbm