CAMB: matter-dominated cosmologies

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Nikos Samaras
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Joined: November 11 2022
Affiliation: Astronomical Institute of Charles University
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CAMB: matter-dominated cosmologies

Post by Nikos Samaras » November 11 2022

Hello,

I would like reproduce the figure 2 of the arXiv:astro-ph/0309240 (Large-scale surveys and cosmic structure J.A. Peacock 2003). This is the about the Transfer function of matter dominated cosmologies. I would like to see the behaviour of the different components (baryons, CDM, HDM, MDM?).

Can I do this with CAMB? When attempted, I was having errors saying:
"Your matter densities are strange (may not have been set)
Invalid parameter value
ERROR STOP Invalid parameter"

Although the plot doesn't indicate the redshift, I would like to see it at z = 250.

Can anyone give me a hint?

Regards,
Nick

Antony Lewis
Posts: 1842
Joined: September 23 2004
Affiliation: University of Sussex
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Re: CAMB: matter-dominated cosmologies

Post by Antony Lewis » November 12 2022

You can use standard parameters and plot the transfer functions for different variables. e.g. see box 48

https://camb.readthedocs.io/en/latest/CAMBdemo.html

and

https://camb.readthedocs.io/en/latest/transfer_variables.html

Nikos Samaras
Posts: 2
Joined: November 11 2022
Affiliation: Astronomical Institute of Charles University
Contact:

Re: CAMB: matter-dominated cosmologies

Post by Nikos Samaras » November 18 2022

Hello,

sorry but I don't really understand what you say. I am actually plotting the TF for different variables but my question is how can I simulate a universe with Omega_m = 1 (Omega_bar = 1 or Omega_CDM =0 or Omega_nu = 1), Omega_DE = 0, Omega_k = 0 .

Isn't it Σ_i Ω_i =1 ?

When tried:
Om_b h^2 = 0.023157
Om_c h^2 = 0.000000
Om_nu h^2 = 4.000000

I am having:
Om_darkenergy = *********
Om_K = 0.000000
Om_m (inc Om_u) = 16.092628
100 theta (CosmoMC) = 1.222761
N_eff (total) = 4.044000
at z =******* sigma8 (all matter) = 0.0004
at z =******* sigma8^2_vd/sigma8 = 0.0004

Does it make sense?

Thanks in advance,
Nick

Antony Lewis
Posts: 1842
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

Re: CAMB: matter-dominated cosmologies

Post by Antony Lewis » November 19 2022

Looks like a weird cosmology, you don't have very low H0, so Omega_de is negative? I don't know exactly how far away from sensible models CAMB will work, it's certainly not much tested for them.

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