lookback_time

astropy.cosmology.lookback_time(*args, **kwargs)

Deprecated since version 0.4: The lookback_time function is deprecated and may be removed in a future version. Use <Cosmology object>.lookback_time instead.

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 : Quantity

Lookback time at each input redshift.

See also

z_at_value

Find the redshift corresponding to a lookback time.