What if there was an event(source)) picked up by Chandra, detected
opposite the center of the universe, 20 billion l/y away, and moving
toward us, not expanding or moving away. Could we possibly "see"
something that did not originate from "our" universe?
This is counterintuitive, but the
universe is actually 156 billion light years wide, according to a NASA
study of 2 years ago, because of what happens to light when the universe
expands (they may have released a revised number more recently but I didn't
see a press release about it). Please see:
There is interesting discussion in the section given under "Impossible?
Cornish explains further".
To directly address your question, no event or source can move fast enough
to overcome the expansion of the universe that is faster than the
speed of light.