Running CosmoMC only with BICEP2 data sets

[Cheng Cheng]

Hi, there

I want to run CosmoMC only with BICEP2 data sets to constrain the parameters.

But it always stopped with following warning:

"
Reionization_zreFromOptDepth: Did not converge to optical depth
tau = 0.175832203639804 optical_depth = 0.230622898755124
50.0000000000000 49.9984741210938

"

What's the problem? Thanks a lot !

The .ini file is setting as:

Code: Select all

#DEFAULT(batch1/CAMspec_defaults.ini)
#DEFAULT(batch1/lowLike.ini)
#DEFAULT(batch1/lowl.ini)

cmb_dataset[BICEP2]=data/BICEP/BICEP2.dataset
#for r>0 also need this:
compute_tensors = T

#planck lensing
DEFAULT(batch1/lensing.ini)

#Other Likelihoods
#DEFAULT(batch1/BAO.ini)
#DEFAULT(batch1/HST.ini)
#DEFAULT(batch1/Union.ini)
#DEFAULT(batch1/SNLS.ini)
#DEFAULT(batch1/WiggleZ_MPK.ini)
#DEFAULT(batch1/MPK.ini)

#general settings
DEFAULT(batch1/common_batch1.ini)

#high for new runs
MPI_Max_R_ProposeUpdate = 30

propose_matrix= 
#planck_covmats/base_planck_lowl_lowLike.covmat

start_at_bestfit =F
feedback=1
use_fast_slow = T

#sampling_method=7 is a new fast-slow scheme good for Planck
sampling_method = 7
dragging_steps  = 3
propose_scale = 2

indep_sample=0

#Folder where files (chains, checkpoints, etc.) are stored
root_dir = chains/

#Root name for files produced
file_root= pivot_test_0.004_0325_tau_lim_3rd
#action= 0 runs chains, 1 importance samples, 2 minimizes
#use action=4 just to quickly test likelihoods
action = 0

#these are just small speedups for testing
get_sigma8=F

[Antony Lewis]

If you are only running with BICEP then there's nothing (except very indirectly the lensing BB) to constrain the reionization optical depth, so it is probably going up to large values. I suggest you fix tau, include a prior on it, or use some other data. Or if you really want to vary tau over a wide range modify the reionization module of CAMB accordingly.

[Cheng Cheng]

If you are only running with BICEP then there's nothing (except very indirectly the lensing BB) to constrain the reionization optical depth, so it is probably going up to large values. I suggest you fix tau, include a prior on it, or use some other data. Or if you really want to vary tau over a wide range modify the reionization module of CAMB accordingly.

Thanks a lot! I'll have a try.