Method

NumCosmoDistancedrag_redshift

Declaration [src]

gdouble
nc_distance_drag_redshift (
  NcDistance* dist,
  NcHICosmo* cosmo
)

Description [src]

Drag redshift is the epoch at which baryons were released from photons.

If the dist object constains a NcRecomb object, it calculates the drag redshift through the recombination history. Otherwise, it computes $z_d$ using the fitting formula given in [Eisenstein & Hu (1998)][XEisenstein1998] [arXiv], $$z_d = \frac{1291 (\Omega_{m0} h^2)^{0.251}}{(1 + 0.659 (\Omega_{m0} h^2)^{0.828})} \left(1 + b_1 (\Omega_{b0} h^2)^{b_2}\right),$$ where $\Omega_{b0} h^2$ [nc_hicosmo_Omega_b0h2()] and $\Omega_{m0} h^2$ [nc_hicosmo_Omega_m0h2()] are, respectively, the baryonic and matter density parameters times the square of the dimensionless Hubble parameter $h$, $H_0 = 100 \, h \, \text{km/s} \, \text{Mpc}^{-1}$. The parameters $b_1$ and $b_2$ are given by $$b_1 = 0.313 (\Omega_{m0} h^2)^{-0.419} \left(1 + 0.607 (\Omega_{m0} h^2)^{0.674}\right) \; \text{and} \; b_2 = 0.238 (\Omega_{m0} h^2)^{0.223}.$$.

Parameters

cosmo

Type: NcHICosmo

A NcHICosmo.

The data is owned by the caller of the method.

Return value

Type: gdouble

$z_d$.