FlatwCDM

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

Bases: astropy.cosmology.wCDM

FLRW cosmology with a constant dark energy equation of state and no spatial curvature.

This has one additional attribute beyond those of FLRW.

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 all redshifts. This is pressure/density for dark energy in units where c=1. A cosmological constant has w0=-1.0.

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 FlatwCDM
>>> cosmo = FlatwCDM(H0=70, Om0=0.3, w0=-0.9)

The comoving distance in Mpc at redshift z:

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

Methods Summary

efunc(z)	Function used to calculate H(z), the Hubble parameter.
inv_efunc(z)	Function used to calculate .

Methods Documentation

efunc(z)

Function used to calculate H(z), the Hubble parameter.

Parameters:

z : array_like

Input redshifts.

Returns:

E : ndarray, or float if input scalar

The redshift scaling of the Hubble consant.

Notes

The return value, E, is defined such that .

inv_efunc(z)

Function used to calculate .

Parameters:

z : array_like

Input redshifts.

Returns:

E : ndarray, or float if input scalar

The inverse redshift scaling of the Hubble constant.

Notes

The return value, E, is defined such that .