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CosmoMC: Massive neutrinos

Posted: May 23 2006
by Vimal Simha
In the original form, the cosmomc code has the number of massive neutrinos = 3, but has the neutrino fraction of dark matter equal to zero.

Am I right in understanding that these are included as a contribution to Omega-radiation before the epoch of matter-radiation equality? Obviously that would depend on the mass.
I was slightly confused about how exactly the code treats this issue. I would be grateful if you could please clarify this.

Re: CosmoMC: Massive neutrinos

Posted: May 24 2006
by Antony Lewis
If the neutrino mass fraction is zero the code knows to interpret 3 massive as 3 massless.

The energy density from neutrinos is included at all times. (though the contribution to \Omega_total today is neglected if they are massless)