Package cosmolopy :: Module density

Module density

Cosmological densities like matter density, baryon density, etc.

Functions

omega_M_z(z, **cosmo)
Matter density omega_M as a function of redshift z.

source code

cosmo_densities(**cosmo)
The critical and mean densities of the universe.

source code

get_X_Y(**cosmo)
The fraction of baryonic mass in hydrogen and helium.

source code

baryon_densities(**cosmo)
Hydrogen number density at z=0.

source code

Variables
	__package__ = `'cosmolopy'`

Function Details

Matter density omega_M as a function of redshift z.

Notes

From Lahav et al. (1991, MNRAS 251, 128) equations 11b-c. This is equivalent to equation 10 of Eisenstein & Hu (1999 ApJ 511 5).

The critical and mean densities of the universe.

rho_crit and rho_0 in solar masses per cubic Megaparsec.

The fraction of baryonic mass in hydrogen and helium.

Assumes X_H + Y_He = 1.

You must specify either 'X_H', or 'Y_He', or both.

Hydrogen number density at z=0.

cosmo: cosmological parameters

parameters used: 'omega_b_0', 'X_H' and/or 'Y_He', plus those needed by cosmo_densities.

rho_crit, rho_0, n_He_0, n_H_0

The first two are in units of solar masses per cubic Megaparsec. The later two are in number per cubic Megaparsec.