Last modified: December 2024

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/set_xscosmo.html
AHELP for CIAO 4.17 Sherpa

set_xscosmo

Context: modeling

Synopsis

Set the cosmological parameters used by X-Spec models.

Syntax

set_xscosmo(h0, q0, l0)

Description

Set the cosmological parameters (H_0, q_0, lambda_0) used by X-Spec. It is equivalent to the X-Spec cosmo command [1] . The default values are h0=70, q0=0, and l0=0.73


Example

>>> set_xscosmo(73, 0, 0.73)

PARAMETERS

The parameters for this function are:

Parameter Type information Definition
h0 number The Hubble constant in km/s/Mpc.
q0 number The deceleration parameter.
l0 number The cosmological constant. If this is non-zero then the q0 parameter is ignored and the Universe is assumed to be flat.

References

XSPEC version

CIAO 4.17 comes with support for version 12.14.0k of the XSPEC models. This can be checked with the following:

% python -c 'from sherpa.astro import xspec;
print(xspec.get_xsversion())'
12.14.0k

Bugs

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

See Also

modeling
get_xscosmo