lookback_time

Protocols

StandardCosmology.lookback_time()

DistanceMeasures.lookback_time()

LookbackDistanceMeasures.lookback_time()

HasLookbackTime.lookback_time()

Reference

cosmo.lookback_time(z: InputT, /) → Array

cosmo.lookback_time(z1: InputT, z2: InputT, /) → Array

Lookback time in Gyr.

The lookback time is the time that it took light from being emitted at one redshift to being observed at another redshift. Effectively it is the difference between the age of the Universe at the two redshifts.

Parameters:

zArray, positional-only

z1, z2Array, positional-only

Input redshifts. If one argument z is given, the time \(t_T(0, z)\) is returned. If two arguments z1, z2 are given, the time \(t_T(z_1, z_2)\) is returned.

Returns:

Array

The lookback time in Gyr.