Flatw0waCDM

class astropy.cosmology.Flatw0waCDM(H0, Om0, w0=-1.0, wa=0.0, Tcmb0=2.7250000000000001, Neff=3.04, m_nu=<Quantity 0.0 eV>, name=None)

Bases: astropy.cosmology.w0waCDM

FLRW cosmology with a CPL dark energy equation of state and no 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): .

Parameters:

H0 : float or Quantity

Hubble constant at z = 0. If a float, must be in [km/sec/Mpc]

Om0 : float

Omega matter: density of non-relativistic matter in units of the critical density at z=0.

w0 : float

Dark energy equation of state at z=0 (a=1). This is pressure/density for dark energy in units where c=1.

wa : float

Negative derivative of the dark energy equation of state with respect to the scale factor. A cosmological constant has w0=-1.0 and wa=0.0.

Tcmb0 : float or Quantity

Temperature of the CMB z=0. If a float, must be in [K]. Default: 2.725.

Neff : float

Effective number of Neutrino species. Default 3.04.

m_nu : Quantity

Mass of each neutrino species. If this is a scalar Quantity, then all neutrino species are assumed to have that mass. Otherwise, the mass of each species. The actual number of neutrino species (and hence the number of elements of m_nu if it is not scalar) must be the floor of Neff. Usually this means you must provide three neutrino masses unless you are considering something like a sterile neutrino.

name : str

Optional name for this cosmological object.

Examples

>>> from astropy.cosmology import Flatw0waCDM
>>> cosmo = Flatw0waCDM(H0=70, Om0=0.3, w0=-0.9, wa=0.2)

The comoving distance in Mpc at redshift z:

>>> z = 0.5
>>> dc = cosmo.comoving_distance(z)