w0wzCDM¶

class astropy.cosmology.core.w0wzCDM(H0, Om0, Ode0, w0=-1.0, wz=0.0, Tcmb0=2.725, Neff=3.04, name='w0wzCDM') [edit on github][source]¶

Bases: astropy.cosmology.core.FLRW

FLRW cosmology with a variable dark energy equation of state and curvature.

The equation for the dark energy equation of state uses the simple form: $w(z) = w_0 + w_z z$ .

This form is not recommended for z > 1.

Examples

>>> from astro.cosmology import wawzCDM
>>> cosmo = wawzCDM(H0=70, Om0=0.3, Ode0=0.7, w0=-0.9, wz=0.2)

The comoving distance in Mpc at redshift z:

>>> dc = cosmo.comoving_distance(z)

Attributes Summary

`w0`	Dark energy equation of state at z=0
`wz`	Derivative of the dark energy equation of state w.r.t.

Methods Summary

`w`(z)	Returns dark energy equation of state at redshift `z`.
`de_density_scale`(z)	Evaluates the redshift dependence of the dark energy density.

Attributes Documentation

w0[source]¶: Dark energy equation of state at z=0

wz[source]¶: Derivative of the dark energy equation of state w.r.t. z

Methods Documentation

w(z) [edit on github][source]¶

Returns dark energy equation of state at redshift z.

Parameters :

z : array_like

Input redshifts.

Returns :

w : ndarray, or float if input scalar

The dark energy equation of state

Notes

The dark energy equation of state is defined as $w(z) = P(z)/\rho(z)$ , where $P(z)$ is the pressure at redshift z and $\rho(z)$ is the density at redshift z, both in units where c=1. Here this is given by $w(z) = w_0 + w_z z$ .