Forerunner WoMD 3

Perhaps most impressive was the ability to suspend much of the wheel in time, lock it in stasis, turning the installation into a great, reflective ring immune to all changes imposed from outside.

But the energy cost of such suspension was immense—perhaps more than the wheel could muster. As well, all around the system, energy that would have been absorbed by the Halo would have to be deflected through a fractal-dimensioned slipspace, creating a suspicious scatter of heat signatures and even high-energy radiation that could attract the attention of anything hunting us.
(Halo:Primordium; Ch.33)