The role of bbn_consistency flag in CosmoMC

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Erick Almaraz
Posts: 25
Joined: June 10 2012
Affiliation: University of Mexico

The role of bbn_consistency flag in CosmoMC

Post by Erick Almaraz » November 10 2016

Hello everybody.

I have some doubts on the role of the bbn_consistency flag in CosmoMC. First of all, by default this flag is set to T in batch2/params_CMB_defaults.ini:

Code: Select all

bbn_consistency = T
As far as I see, this means that we use the Parthenelope fitting table (at $COSMOMC/data) just to calculate the primordial abundances of helium and deuterium as a function of omegabh2 and the extra relativistic number of species (see source/CosmologyParametrizations). These calculations are just theoretical predictions, since the program does not handle observational data on that subject against which these predictions can be compared. Am I right?

Regards

Antony Lewis
Posts: 1379
Joined: September 23 2004
Affiliation: University of Sussex
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Re: The role of bbn_consistency flag in CosmoMC

Post by Antony Lewis » November 10 2016

That's right. (there is a dataset format for element abundance data as well)

Erick Almaraz
Posts: 25
Joined: June 10 2012
Affiliation: University of Mexico

The role of bbn_consistency flag in CosmoMC

Post by Erick Almaraz » November 10 2016

Dear Antony. Thanks for the quick reply. I suppose that the abundance data you mention is the Cooke's and Izotov's measurements of primordial deuterium and helium, respectively (these data can be found at $COSMOMC/data/D_Cooke2013.dataset & Yp_Izotov2014.dataset). If I'd like to take into account this information in my analysis, I guess that I would have to include batch2/abundances.ini in my ini file. Am I right?

Regards

Antony Lewis
Posts: 1379
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

Re: The role of bbn_consistency flag in CosmoMC

Post by Antony Lewis » November 11 2016

Yes, just include/edit batch2/abundances.ini as required.

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