### BAO + BBN constraints on H0

Posted:

**July 09 2019**Hi all,

I would like to reproduce Figures 3(Left) and 4 of this paper (https://arxiv.org/abs/1707.06547), using CosmoMC. For that matter I'd like to understand how to combine the two data sets of Galaxy BAO and Lya BAO like done in Figure 3. As written in the paper the D/H constraint is applied via a Omegabh^2 Gaussian prior... how do I add that?

So far I computed several chains using the different BAO data using a modified test.ini for the respective data set.. e.g.:

But I'm not sure if I'm missing something crucial...

Sorry if these things are obvious, but I'm fairly new to CosmoMC and MCMC procedure and it's not straight forward for me.

Thanks,

Conrad

I would like to reproduce Figures 3(Left) and 4 of this paper (https://arxiv.org/abs/1707.06547), using CosmoMC. For that matter I'd like to understand how to combine the two data sets of Galaxy BAO and Lya BAO like done in Figure 3. As written in the paper the D/H constraint is applied via a Omegabh^2 Gaussian prior... how do I add that?

So far I computed several chains using the different BAO data using a modified test.ini for the respective data set.. e.g.:

Code: Select all

```
#general settings
#Bicep-Keck-Planck 2015, varying cosmological parameters
DEFAULT(batch3/BK15.ini)
#Planck 2018
DEFAULT(batch3/lensing.ini)
#Other Likelihoods
DEFAULT(batch3/DR14_LYxQSO_BAO.ini)
#general settings
DEFAULT(batch3/common.ini)
#high for new runs
MPI_Max_R_ProposeUpdate = 30
propose_matrix= planck_covmats/base_TT_lowTEB_plik.covmat
#Folder where files (chains, checkpoints, etc.) are stored
root_dir = chains/
#Root name for files produced
file_root=test
#action= 0 runs chains, 1 importance samples, 2 minimizes
#use action=4 just to quickly test likelihoods
action = 0
#expected result for -(log like)
test_check_compare = 663.808
num_threads = 0
start_at_bestfit =F
feedback=1
use_fast_slow = T
checkpoint = T
#sampling_method=7 is a new fast-slow scheme good for Planck
sampling_method = 7
dragging_steps = 3
propose_scale = 2
#Set >0 to make data files for importance sampling
indep_sample=10
#these are just small speedups for testing
get_sigma8=T
```

Sorry if these things are obvious, but I'm fairly new to CosmoMC and MCMC procedure and it's not straight forward for me.

Thanks,

Conrad