[CAMB] Adjust omage lambda in python wrapper

[Hadi Sotoudeh]

Hi,

I am using CAMB's Python wrapper, and I need to adjust the value of the dark energy density parameter, assuming it is in the form of a cosmological constant ([math]\Omega_\Lambda). I have two questions:

1) Is the value of [math]\Omega_\Lambda deduced using the following formula?

[math]\Omega_\Lambda = 1 - \Omega_c - \Omega_b - \Omega_\nu - \Omega_k

If not, what is the formula to deduce [math]\Omega_\Lambda from CAMB inputs? Here, [math]\Omega_c, \Omega_b, \Omega_\nu are the density parameters of CDM, baryons, and massive neutrinos, respectively. [math]\Omega_i = \rho_i \times \frac{8\pi G}{3H^2}. Also, [math]\Omega_k = - \frac{kc^2}{a^2H^2}.


2) Let's say I would like to run CAMB with the following parameter combinations:

1. Flat Universe, with a specific [math]\Omega_\Lambda value, say 0.34.
2. Curved Universe, with the same density parameters as [math]\LambdaCDM but a non-zero curvature.
3. Curved Universe, with no cosmological constant ([math]\Omega_\Lambda) and a non-zero curvature.

What values should be passed to camb.set_params() for the following arguments: ombh2, omch2, omnuh2, omk. Are there any other arguments that need to be set?

Thank you very much for your time and attention! 💐

[Antony Lewis]

Yes, you need to also pass H0 or thetastar.