w0waCDM¶

class astropy.cosmology.core.w0waCDM(H0, Om0, Ode0, w0=-1.0, wa=0.0, Tcmb0=2.725, Neff=3.04, name='w0waCDM') [edit on github][source]¶

Bases: astropy.cosmology.core.FLRW

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

The equation for the dark energy equation of state uses the CPL form as described in Chevallier & Polarski Int. J. Mod. Phys. D10, 213 (2001) and Linder PRL 90, 91301 (2003): $w(z) = w_0 + w_a (1-a) = w_0 + w_a z / (1+z)$ .

Examples

>>> from astro.cosmology import w0waCDM
>>> cosmo = w0waCDM(H0=70, Om0=0.3, Ode0=0.7, w0=-0.9, wa=0.2)

The comoving distance in Mpc at redshift z:

>>> dc = cosmo.comoving_distance(z)

Attributes Summary

`wa`	Negative derivative of dark energy equation of state w.r.t.
`w0`	Dark energy equation of state at z=0

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

wa[source]¶: Negative derivative of dark energy equation of state w.r.t. a

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

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 $w(z) = w_0 + w_a (1 - a) = w_0 + w_a \frac{z}{1+z}$ .