[CosmoMC] Parameterization of omnuh2

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
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Alan Knee
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Joined: May 12 2018
Affiliation: University of British Columbia

[CosmoMC] Parameterization of omnuh2

Post by Alan Knee » August 08 2018

In Calculator_Cosmology.f90, it says

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real(mcp), parameter :: neutrino_mass_fac= 94.07_mcp !conversion factor for thermal with Neff=3 TCMB-2.7255
!93.014 for 3.046
real(mcp), parameter :: standard_neutrino_neff = 3.046_mcp
and in CosmologyParameterizations.f90 it calculates omnuh2 as follows

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CMB%omnuh2=Params(6)/neutrino_mass_fac*(standard_neutrino_neff/3)**0.75_mcp
where Params(6) = mnu. If I understand correctly, the factor of (3.046/3)^(3/4) is meant to account for the fact that standard N_eff is slightly greater than 3. Multiplying by this factor results in omnuh2 = mnu/93.0025 eV, but shouldn't the denominator be 93.014 as stated in the other file?

Antony Lewis
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Joined: September 23 2004
Affiliation: University of Sussex
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Re: [CosmoMC] Parameterization of omnuh2

Post by Antony Lewis » August 08 2018

I think 93.014 is for $T_{\rm CMB}= 2.726 {\rm K}$.

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