## Warning: xe at redshift zero is < 1 in CosmoMC

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
srijita sinha
Posts: 32
Joined: April 12 2019
Affiliation: Indian Institute of Science Education and Research Kolkata

### Warning: xe at redshift zero is < 1 in CosmoMC

Hi,

I am a novice in CosmoMC and please pardon if it is a trivial question and already answered.

I want to constrain the six parameter CDM model with fsigma8 data given in table: III of https://arxiv.org/abs/1703.10538.
For that, I have written a likelihood similar to bao.f90. When I am using only the fsigma8 data with action = 2, I am getting the minimum values. But when I am using it with action = 0, it is not constraining , and well. The contour plots look blotchy even after increasing the range. The code stops with the error

Code: Select all

CAMB error ThemoData Init: failed to find the end of recombination
When I am using both Planck 2018 and fsigma8, I am getting nice contours but the error message,

Code: Select all

Warning: xe at redshift zero is < 1

Check input parameters a Reionization_xe

function in the Reionization module
is there.
I understand it is related to CAMB. What is it that I need to take care?
I did not change any parameter value given in CosmoMC May 2020.

Antony Lewis
Posts: 1807
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

### Re: Warning: xe at redshift zero is < 1 in CosmoMC

If you are only using fsigma8 you should fix unconstrained parameters.

The second message is probably harmless, though that should not happen at all often with Planck data.

srijita sinha
Posts: 32
Joined: April 12 2019
Affiliation: Indian Institute of Science Education and Research Kolkata