CAMB : .ini definitions

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
Post Reply
Frederic Vincent
Posts: 4
Joined: July 26 2007
Affiliation: Institut d'Astrophysique de Paris

CAMB : .ini definitions

Post by Frederic Vincent » July 26 2007

Hi,

I'm working on massive neutrinos and I would like to know the precise definition of the following items in params.ini :

- massless_neutrinos
- massive_neutrinos
- nu_mass_fractions

In particular, is massless_neutrinos equivalent to the effective number of neutrinos (N_eff or N_nu in most papers) ? Is it the case even if massive_neutrinos differs from 0?

I'd also like to know how I can obtain power spectra for different redshifts (e.g. from z=4 to z=0 with Delta_z=0.1).

Thanks a lot,

Frederic

Antony Lewis
Posts: 1941
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

Re: CAMB : .ini definitions

Post by Antony Lewis » July 26 2007

Yes, QED effects etc are usually accounted for by an effective number of massless_neutrinos (e.g. astro-ph/0111408). Since massive neutrinos are relativistic in the early universe anyway I usually always put the fractional number into the massless neutrinos, but I don't have an other justification for doing this (though I'm not sure the code would work with a fractional number of massive neutrinos).

Change transfer_redshift(x) to set the redshift for each transfer function/matter power spectrum.

Post Reply