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lesgourg / class_public

Public repository of the Cosmic Linear Anisotropy Solving System (master for the most recent version of the standard code; GW_CLASS to include Cosmic Gravitational Wave Background anisotropies; classnet branch for acceleration with neutral networks; ExoCLASS branch for exotic energy injection; class_matter branch for FFTlog)
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tensor scalar ration constraint #561

Open ming-jian opened 7 months ago

ming-jian commented 7 months ago

Hello everyone,

I want to obtain the constraint on the tensor scalar ratio 'r' using the MontePython + CLASS. However, the output for r is r = 1. I modify the base2018TTTEEE.param as follows:

data.cosmo_arguments['Pk_ini_type'] = 'analytic_Pk' data.cosmo_arguments['k_pivot'] = 0.05 data.cosmo_arguments['modes'] = 's,t' data.cosmo_arguments['n_t'] = 'scc' data.cosmo_arguments['alpha_t'] = 'scc'

The result is r = 1.

data.cosmo_arguments['Pk_ini_type'] = 'external_Pk' data.cosmo_arguments['k_pivot'] = 0.05 data.cosmo_arguments['modes'] = 's,t' data.cosmo_arguments['n_t'] = 'scc' data.cosmo_arguments['alpha_t'] = 'scc'

The chains stop and shows: Something went wrong when calling CLASS /o\ Error in Class: Class did not read input parameter(s): n_t, alpha_t, n_s, A_s

I want to know where the problem is . And how to obtain a constraint for ratio r ?

Thanks very much!

brinckmann commented 7 months ago

Hi Ming-Jian,

In the first case r takes the default value of 1 since you didn't change it. You might include r as a varying cosmological parameter if you want to constrain it. I think what you have would work if you do that. Remember to add it next to the other cosmo parameters in the param file as you normally do with varying parameters, and impose the appropriate parameter limits (r > 0).

In the second case you're supposed to input a file with a table or code that gives CLASS the P(k), so it doesn't use those parameters.

Best, Thejs