You can incorporate Pico into CosmoMC by downloading Pico and a set of data files below. Then follow the directions in the manual explaining how to use Pico to compute the CMB power spectra, matter transfer function and the WMAP3 likelihood.¹

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Here you will find various available sets of regression coefficients that are required for Pico to compute power spectra and likelihoods. The files differ in the cosmological parameters that are allowed to vary. You will then need to tell Pico where the regression files are, see the manual for some straight forward instructions.

Note that it is safe to fix parameters that Pico allows you to vary, however you must ensure that you are not varying parameters that Pico does not use in its regression.

pico_data-open_w_r.tgz (29MB)

Allows varying 9 parameters:

• &Omega_bh²
• &Omega_cdmh²
• &Omega_k
• &theta
• &tau
• n_s
• The dark energy equation of state (w_DE)
• The scalar amplitude (A_s)
• The tensor/scalar ratio (r)
• Allows computation of the TT, TE, EE and BB power spectra due to scalar and tensor modes out to l_max=3000.
• Also allows computation of the matter transfer function and the WMAP3 likelihood. Does not compute the lensed power spectra.

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If you use Pico please cite: W. A. Fendt and B. D. Wandelt, Astrophys. J. 654, 2 (2007) and W. A. Fendt and B. D. Wandelt, Astrophys. J. submitted [astro-ph//0712.0194].

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¹ Pico is trained using the results of the officially released WMAP 3yr likelihood (version: v2p2p2) using the preprocessor commands -DFASTERTT -DOPTIMIZE and with the default offset values in WMAP_3yr_options.F90.

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