Internals
The following types and methods are internal, and should not be considered safe for public use.
Types
Cosmology.AbstractCosmology — Type
abstract type AbstractCosmologyAbstract supertype for all cosmological models.
Cosmology.LCDM — Type
struct LCDM{T<:Real} <: Cosmology.AbstractCosmologyΛCDM model of the universe.
Cosmology.WCDM — Type
struct WCDM{T<:Real} <: Cosmology.AbstractCosmologywCDM model of the universe, which includes a cosmological equation of state parameter w.
Methods
Cosmology.E — Function
E(c::AbstractCosmology, z)Dimensionless Hubble function $E(z)$ at redshift z. It's defined as
\[E(z) ≡ \frac{H(z)}{H_0} = \frac{H(z)}{(100\mathrm{km/s/Mpc}) h}\]
where $H_0 = H(z=0)$ is the Hubble parameter at the present epoch (Schneider 2015, p. 183).
Cosmology.Z — Function
Z(c::AbstractCosmology, z, nothing; kws...)
Z(c::AbstractCosmology, z₁, z₂; kws...)The line-of-sight comoving distance contributions for comoving radial distance.
It performs the integral
\[Z = \int_{z_1}^{z_2} \frac{dz}{E(z)} = \int_{a_2}^{a_1} \frac{da}{a^2 E(a)}\]
where we can perform a change of variables with $a = 1/(1+z)$, and $dz = -da/a^2$.
If nothing is used for the second bound of integration, it defaults to z₁ = 0 (i.e., a₁ = 1).
See also
Cosmology.T — Function
T(c::AbstractCosmology, a0, a1; kws...)The line-of-sight contributions for lookback time.
It performs the integral
\[T = \int_{a_0}^{a_1} \frac{da}{a E(a)}\]
Cosmology.a2E — Function
a2E(c::AbstractCosmology, a)Calculates the intermediate quantity $a^2 E(a)$. This is an internal function used to simplify computation.
Mathematical definition for ΛCDM models:
\[a^2 E(a) = \sqrt{Ω_r + Ω_m a + Ω_k a^2 + Ω_Λ a^4}\]
and for wCDM models:
\[a^2 E(a) = \sqrt{Ω_r + Ω_m a + Ω_k a^2 + Ω_Λ a_{de}}\]
where $Ω_k = 0$ for a flat cosmological model, and $a_{de} = a^{1 - 3(w_0 + w_a)} \exp(3 w_a (a - 1))$ (Scherrer, 2015).