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Last modified: December 2015

URL: http://cxc.harvard.edu/sherpa/ahelp/set_xscosmo.html
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AHELP for CIAO 4.9 Sherpa v1

set_xscosmo

Context: modeling

Synopsis

Set XSPEC cosmology settings (H0, q0, L0)

Syntax

set_xscosmo(H0, q0, L0)
get_xscosmo()

Description

The set_xscosmo command specifies the cosmology settings (H0, q0, L0) used in XSPEC models.

The get_xscosmo command returns the current setting.

  • H0 - the Hubble constant in km/s/Mpc; default is 70
  • q0 - the deceleration parameter; default is 0
  • L0 - the cosmological constant; default is 0.73

If the cosmological constant is non-zero, then the value of q0 will be ignored and it is assumed that Omega_matter is >= 1-L0.

XSPEC version

This information is taken from the XSPEC User's Guide. Version 12.9.0o of the XSPEC models is supplied with CIAO 4.9.

Example

sherpa> print(get_xscosmo())
(70.0, 0.0, 0.7300000190734863)
sherpa> set_xscosmo(100, 0, 0.7)

The current cosmology setting is retrieved, and then changed to H0 = 100 km/s/Mpc, q0 = 0, and lambda0 = 0.7.

Bugs

For a list of known bugs and issues with the XSPEC models, please visit the XSPEC bugs page.

To check the X-Spec version used by Sherpa, use the get_xsversion routine from the xspec module:

sherpa> from sherpa.astro.xspec import get_xsversion
sherpa> get_xsversion()
'12.9.0o'

See Also

confidence
set_conf_opt, set_covar_opt, set_proj_opt
data
get_bkg_plot, set_areascal, set_arf, set_backscal, set_bkg, set_coord, set_counts, set_data, set_exposure, set_grouping, set_quality, set_rmf, set_staterror, set_syserror
filtering
set_filter
info
list_model_ids, show_bkg_model, show_bkg_source
methods
set_iter_method, set_iter_method_opt, set_method, set_method_opt
modeling
add_model, add_user_pars, clean, create_model_component, delete_bkg_model, delete_model, delete_model_component, get_model, get_model_autoassign_func, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_order_plot, get_par, get_pileup_model, get_source, get_source_component_image, get_source_component_plot, image_model, image_model_component, image_source, image_source_component, integrate, integrate1d, link, load_table_model, load_template_model, load_user_model, normal_sample, reset, save_model, save_source, set_bkg_model, set_full_model, set_model_autoassign_func, set_par, set_pileup_model, set_source, set_xsabund, set_xsxsect, set_xsxset, t_sample, uniform_sample
plotting
get_lrt_plot, get_lrt_results, get_pvalue_plot, get_pvalue_results, plot_cdf, plot_model, plot_model_component, plot_pdf, plot_pvalue, plot_scatter, plot_source, plot_source_component, plot_trace
psfs
delete_psf, load_conv
saving
save_delchi, save_resid
statistics
set_prior, set_sampler, set_sampler_opt, set_stat
utilities
calc_chisqr, calc_energy_flux, calc_model_sum, calc_photon_flux, calc_source_sum, calc_stat, eqwidth, set_analysis, set_default_id
visualization
contour_model, contour_ratio, contour_resid, get_ratio, get_resid, image_setregion

Last modified: December 2015
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