Sub-hyperspace

Sub-hyperspace was the name given by members of the First Order to a hole in the space-time continuum through which phantom energy traveled. Unlike typical hyperspace, which moved across the galaxy, sub-hyperspace would move through the galaxy. The First Order's Starkiller Base was able to collect a form of dark energy called quintessence, transform it into phantom energy, and unleash it along a linear path through sub-hyperspace, enabling it to destroy entire star systems across vast interstellar distances in real-time.

Text and facts from the “Sub-hyperspace” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.