## neutrino distribution

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
Rui Hu
Posts: 2
Joined: February 15 2023
Affiliation: Chinese University of Hong Kong

### neutrino distribution

Hi everyone,

I am confused about the neutrino distribution function in CAMB and COSMOMC. So basically, it seems we have two choices:

and a thermal one where

which one is actually used in CAMB and COMSOMC(it looks to me the thermal one) and why? And in COSMOMC why do we need to times to get the but for seterile neutrino we just use

BTW, especially for sterile neutrino, prof S.Pastor argued in arxiv1905.11290v3 that the first disturbution is more accurate than the thermal one. I would like to hear your comments if it uses thermal distribution in CAMB.

Antony Lewis
Posts: 1872
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

### Re: neutrino distribution

The neutrino model is described in the CAMB notes. meffsterile is defined as in the Planck parameter papers.

Rui Hu
Posts: 2
Joined: February 15 2023
Affiliation: Chinese University of Hong Kong

### Re: neutrino distribution

now I understand. Thanks a lot!