Transfer redshift-tauend conversion

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Abir Sarkar
Posts: 16
Joined: July 07 2014
Affiliation: Raman Research Institute

Transfer redshift-tauend conversion

Post by Abir Sarkar » March 10 2015

As far as I have understood, The code solves the equations until the transfer redshift provided by the user. The equations are written in terms of the conformal time tau and the integration is also on tau, starting from taustart and up to tauend.

Can someone please tell me how and where(in the code) the conversion between this transfer redshift, provided by user in params.ini, and tauend is taking place??

Antony Lewis
Posts: 1941
Joined: September 23 2004
Affiliation: University of Sussex
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Re: Transfer redshift-tauend conversion

Post by Antony Lewis » March 10 2015

See TimeOfz in modules.f90.

Abir Sarkar
Posts: 16
Joined: July 07 2014
Affiliation: Raman Research Institute

Transfer redshift-tauend conversion

Post by Abir Sarkar » March 11 2015

First, thanks a lot for the help. I have one more query. I want to add one more redshift , let's call in as "intermediate redshift" , along with transfer redshift in the params.ini. I want to get the transfer function at this redshift along with transfer redshift. How to do it and include it in the other .f90 files?

Probably it is allowed to get the transfer functions at more than one transfer redshift in CAMB, but that is not what I am looking for.

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

Re: Transfer redshift-tauend conversion

Post by Antony Lewis » March 12 2015

I don't think I've understood how what you are asking for is different from the transfer function at another redshift (possible, as you say, from the ini file).

Abir Sarkar
Posts: 16
Joined: July 07 2014
Affiliation: Raman Research Institute

Transfer redshift-tauend conversion

Post by Abir Sarkar » March 12 2015

Let me describe the physics of the problem

Initially we are assuming that there is no dark matter in the universe. Then at a certain redshift z_{form} dark matter is produced from massless neutrino(I am not giving the detailed particle physics scenario which is irrelevant). So, at z=z_{form} the dark matter is getting there their initial condition form the final conditions of massless neutrino.

The code will do the following:
It will integrate the perturbation equations from tau=taustart to tau=tau_{form} assuming no dark matter. We will write the transfer function of all the species at z=z_{form} and use that of massless neutrino for the initial condition of dark matter. Then with this new initial condition the code will run from z=z_{form} to z=0 to give the transfer function at present.

The formation redshift, which I called the intermediate redshift in the previous thread, will be there in the params.ini and will be provided by the user. How to include this new parameter there and what changes are needed to be made in other codes?

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