(covers information from several alternate timelines)
A temporal wake is an energetic phenomenon that can be created as a byproduct of a temporal vortex, insulating anything caught inside from an alteration of the timeline.
In 2373, a Borg sphere generated a temporal vortex to the year 2063, where they changed history by stopping Zefram Cochrane's first warp flight, and assimilating humanity. Having become caught in the vortex's wake, the USS Enterprise-E remained unaffected by the alteration to history, allowing the crew to follow the sphere through the vortex and restore the timeline. (Star Trek: First Contact)