[ELI5] if a (relatively) small black hole is orbiting a more massive black hole, as they eventually merge, would the matter be drawn back out of the singularity of the smaller?

Question

I understand that they consume matter and grow, and that black holes merge to form larger ones. But I’m curious if scientist know whether or not this takes place bit by bit, or whether because the matter can’t escape the singularity of the smaller one, it would be a case of the entire thing being eaten up all at once?

If the latter is the case, would this happen in an instant with a reaction, or just a slow process as it all gets enveloped?

To clarify: I’m aware that in some cases, ultramassive black holes have other black holes orbiting them, because I watched the kurzgesagt video on it, but that’s the extent of my knowledge

Many thanks

In: Planetary Science

Answer 1

The short answer is a firm “no”.

The longer answer is that black holes merge at the event horizon, and the singularities (if they actually exist) are never exposed. In fact from our point of view it’s much better to model black holes as their event horizons, ignoring the interiors completely.

Think of two drops of water merging, they don’t suddenly turn inside out at the last instant. Instead as they approach each other, their exteriors suddenly overcome mutual surface tension and you just have one drop of water. In the case of black holes it’s very similar, and you will have a slightly “wobbly” event horizon for fractions of a second, as the new black hole settles down into a new stable equilibrium.