set_xscosmo

sherpa.astro.xspec.set_xscosmo(h0, q0, l0)[source] [edit on github]

Set the cosmological parameters used by X-Spec models.

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

Parameters:
  • 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.

See also

get_xscosmo(), get_xsversion()

References

[1]http://heasarc.nasa.gov/xanadu/xspec/manual/XScosmo.html Note that this may refer to a newer version than the compiled version used by Sherpa; use get_xsversion to check.

Examples

>>> set_xscosmo(73, 0, 0.73)