It is not a matter of anti-matter. It is a matter of matter, but made so dense that its gravitational pull is phenomenal. Two of them colliding will cause perturbations all across the frequency spectrum, but it is debatable how much of what would actually escape. Ripples in the fabric? Well at least, ripples in the gravity field.

Anti-matter is something else again, rarer by far than black holes. Or so it seems.


A