astropy:docs

lookback_time

astropy.cosmology.funcs.lookback_time(z, cosmo=None)[source] [edit on github]

Lookback time in Gyr to redshift z.

The lookback time is the difference between the age of the Universe now and the age at redshift z.

Parameters :

z : array_like

Input redshifts.

Returns :

t : astropy.units.Quantity

Lookback time at each input redshift.

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