This was a Heavenly Chasm, or rather, a Great Wall of the Universe.
It used the simplest method – a distance far enough to act as the Wall of Sighs that separated the two starfields.
According to the scan results of the sentry formation placed at the edge of this Heavenly Chasm, its current known widest point was at least 20,000 light years, and its length was directly cutting the spiral galaxy into two halves, which was more than 200,000 light-years long.
The central supermassive Black Hole that was used to maintain the overall shape of the vortex was divided into the upper three spiral arms. With this separation, the lower three spiral arms would gradually be thrown out of the spiral galaxy, and only a small portion would be able to reunite with the spiral galaxy.
The upper three spiral arms would become the spiral arms of the spiral galaxy again, maintaining the spiral form of the galaxy as a whole.
"What happened here?"