I think the use of tachyons are worth considering. Also, Dark Energy is out there, and there is little clue as to what it is, though it is far greater than any thing else that exists. Antoniseb's stuff from the earliest time of the Big Bang, when antimatter and matter beat the snout out of each other is good advice because we are becoming more and more comfortable with the fantastic events that took place back then. An anomaly from that time finally reaching your planet is not too far off the scientific trail.
If you need to develop the credibility of the astrophysicist, then more details will be helpful as he gives important advice. As you likely know, usually the fewer details the better, because the greater the details, the greater the scrutiny, and straying from the struggle itself is rarely helpful. Stay balanced.
For example, the last Star Trek introduced Red Matter, but they avoided a ton of questions about its nature by just ignoring them. Nevertheless they spent a little time showing us that is was special stuff. The personal struggles to acquire it and handle it were far more important to the story, and they got away with some whopper holes in their plot.
I hold the view that a person's strength often reveals their weakness. If you give someone superhuman strength, give them an offsetting subhuman weakness. This invites the need of a companion, and opposites attract. 20k words, huh. Ok, nevermind.
Since you're in the UK, you might find this across-the-pond sister forum helpful, too. If nothing else, their time will be a little more agreeable for you, I'll bet.
We know time flies, we just can't see its wings.