The first version of the fgas module was used in:
"Constraining Dark Energy with X-ray Galaxy Clusters, Supernovae and the Cosmic Microwave Background"
Other papers in which the fgas module was used:
"The prospects for constraining dark energy with future X-ray cluster gas mass fraction measurements"
"A kinematical approach to dark energy studies"
* To implement the fgas module to your current version of CosmoMC, either:
fgas_module.tar.gz, which contains the files to calculate the fgas likelihood (source/clusters_xray_fgas.f90, data/cl_xray_fgas.dat) and the modified CosmoMC files (camb/modules.f90, source/calclike.f90, source/CMB_Cls_simple.f90, source/driver.F90, source/params_CMB.f90, source/settings.f90, source/cmbtypes.f90) required to incorporate the fgas files into the rest of the code,
fgas_files.tar.gz, which contains only the fgas files, and follow this documentation to modify the appropiate CosmoMC files.
cosmomc/ directory:tar -zxvf fgas_module.tar.gz will add the fgas files and substitute your CosmoMC files by the modified files; or, tar -zxvf fgas_files.tar.gz will only add the fgas files, and then follow the documentation above to modify the appropiate CosmoMC files).
source/Makefile. Note that if you compile with the option PARAMETERIZATION=params.o (i.e., using the supplied file source/params.f90) you will be able to choose between theta and H_0 as a running parameter. To run CosmoMC with H_0, set, in params_fgas.ini, the option use_theta_param=F, comment out the line of param3 for theta, and uncomment the corresponding line for H_0. Theta is enforced when CMB data is used. When using fgas data alone, H_0 is recommended (faster).
params_fgas.ini. Include the fgas data in your analysis selecting use_XrayClusters=T. If you run the fgas data alone, select use_HST=T and use_BBN=T. If you combine fgas with CMB data, you do not need the HST and BBN priors. Choose between theta or H_0, as discussed above. Under the tag #fgas allowances there are seven new parameters to account for the systematic uncertainties in the fgas experiment (see Allen et al. 2008 for details). A distparams_fgas.ini is also provided.