CosmoCoffee

Hi everyone,

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

[math]f_\nu = g_i \frac{1}{Exp(p/T_\nu)+1} and a thermal one [math]\frac{1}{Exp(p/T_i)+1} where [math]T_i=T_\nu g_i^{1/4}

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 [math](nnu/3)^{3/4} to get the [math]Omnuh2 but for seterile neutrino we just use [math]Omnuh2\_sterile =\frac{meffsterile}{neutrino\_mass\_fac}

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.

Looking forward to your comments!

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

now I understand. Thanks a lot!