What would it look like if dark matter fell into a black hole?

What would it look like if dark matter fell into a black hole? What might you see while it was happening?

Mike Follows, Sutton Coldfield, West Midlands, UK

There would be no discernible difference to the appearance of a black hole. Besides, a small amount of dark matter probably already falls into black holes.

Dark matter doesn’t interact electromagnetically – so cannot emit, absorb or scatter light – but it does respond to the force of gravity, so would fall into a black hole in the same way that ordinary matter does. However, while ordinary matter collapses to form a galactic disc, emitting electromagnetic radiation in…