CosmoMC: Massive neutrinos

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
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Vimal Simha
Posts: 13
Joined: May 11 2006
Affiliation: Ohio State University

CosmoMC: Massive neutrinos

Post by Vimal Simha » May 23 2006

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.

Antony Lewis
Posts: 1501
Joined: September 23 2004
Affiliation: University of Sussex
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Re: CosmoMC: Massive neutrinos

Post by Antony Lewis » May 24 2006

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)

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