Z_eq in CAMB?

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Dan Mainemer
Posts: 2
Joined: March 13 2014
Affiliation: Berkeley

Z_eq in CAMB?

Post by Dan Mainemer » March 13 2014

Hi,

I am running CAMB for different neutrino masses, say Sum_m_nu=0-10 eV, considering a normal hierarchy (just change the neutrino mass, Omega_nu h^2, in the default input, params.ini). I noticed that the program outputs Z_eq, the redshift for matter radiation equality, but the value does not change with the neutrino mass. This seems weird. My understanding is that by increasing neutrino mass, matter radiation equality should occur earlier, since neutrinos became non-relativistic earlier, therefore increasing the (non relativistic matter) mass. Why isn't CAMB accounting for this effect?

Any help will be appreciated,

Dan

Antony Lewis
Posts: 1941
Joined: September 23 2004
Affiliation: University of Sussex
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Re: Z_eq in CAMB?

Post by Antony Lewis » March 14 2014

The program outputs z_EQ (if v_nu=1), i.e. equality defined as though the neutrinos are relativistic. There are of course other possible definitions which are more physical (but harder to calculate).

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