Relation between the turnaround and virial redshifts, z_ta and z_vir. Negative redshift values must be interpreted as future cosmological times; timelines (corresponding age of the Universe) are shown in the right and upper axes. Systems which expansion have turned around at z = 0.4 (green dash-dotted line) or at z = 0.7 (blue dashed line) will be virialised in future (at 17.1 Gyr) or now (at 13.8 Gyr).