Hyperdiction
Hyperdiction is when an Unknown Ship interdicts another ship while traveling through hyperspace. It's in a higher-dimensional region in which travel between star systems is possible at superluminal speeds (many times the speed of light).
Humans only have the technology to interdict ships while travelling with supercruise in a system.
It has occurred around Pleiades and near the Maia system. It doesn't require an unknown artifact in your cargo hold.