What would happen if the golden throne were approached by an untouchable or culexus assassin?

Would it be enough to cut off the Emperor?

Could that potentially outright kill him?

Would his sheer level of power be enough to get around the dead space?

If one wouldn't be enough, how many untouchables would it take to cut the astronomicon off?

Cut off from the beacon, what would happen to the Imperium of Man, how long could it hold together before it fell into bedlam?