FlatFLRWMixin#

class astropy.cosmology.FlatFLRWMixin(*args, **kw)[source]#

Bases: FlatCosmologyMixin

Mixin class for flat FLRW cosmologies.

Do NOT instantiate directly. Must precede the base class in the multiple-inheritance so that this mixin’s __init__ proceeds the base class’. Note that all instances of FlatFLRWMixin are flat, but not all flat cosmologies are instances of FlatFLRWMixin. As example, LambdaCDM may be flat (for the a specific set of parameter values), but FlatLambdaCDM will be flat.

Attributes Summary

`Ode0`	Omega dark energy; dark energy density/critical density at z=0.
`Otot0`	Omega total; the total density/critical density at z=0.
`is_flat`	Return `True`, the cosmology is flat.
`nonflat`	Return the equivalent non-flat-class instance of this cosmology.

Methods Summary

`Otot`(z)	The total density parameter at redshift `z`.
`clone`(*[, meta, to_nonflat])	Returns a copy of this object with updated parameters, as specified.

Attributes Documentation

Ode0#: Omega dark energy; dark energy density/critical density at z=0.

Otot0#: Omega total; the total density/critical density at z=0.

is_flat#: Return True, the cosmology is flat.

nonflat#

Methods Documentation

Otot(z)[source]#

The total density parameter at redshift z.

Parameters:

zQuantity-like [‘redshift’], array_like, or Number: Input redshifts.

Returns:

Ototndarray or float: Returns float if input scalar. Value of 1.

clone(*, meta: Mapping | None = None, to_nonflat: bool = False, **kwargs)#

Returns a copy of this object with updated parameters, as specified.

This cannot be used to change the type of the cosmology, except for changing to the non-flat version of this cosmology.

Parameters:

metamapping or None (optional, keyword-only): Metadata that will update the current metadata.
to_nonflatbool, optional keyword-only: Whether to change to the non-flat version of this cosmology.
**kwargs: Cosmology parameter (and name) modifications. If any parameter is changed and a new name is not given, the name will be set to “[old name] (modified)”.

Returns:

newcosmoCosmology subclass instance: A new instance of this class with updated parameters as specified. If no arguments are given, then a reference to this object is returned instead of copy.

Examples

To make a copy of the Planck13 cosmology with a different matter density (Om0), and a new name:

>>> from astropy.cosmology import Planck13
>>> Planck13.clone(name="Modified Planck 2013", Om0=0.35)
FlatLambdaCDM(name='Modified Planck 2013', H0=<Quantity 67.77 km / (Mpc s)>,
              Om0=0.35, ...

If no name is specified, the new name will note the modification.

>>> Planck13.clone(Om0=0.35).name
'Planck13 (modified)'

The keyword ‘to_nonflat’ can be used to clone on the non-flat equivalent cosmology. For FLRW cosmologies this means Ode0 can be modified:

>>> Planck13.clone(to_nonflat=True, Ode0=1)
LambdaCDM(name='Planck13 (modified)', H0=<Quantity 67.77 km / (Mpc s)>,
          Om0=0.30712, Ode0=1.0, ...