A supermassive black hole that can't stop erupting

If there’s one thing you learn when you study astronomy, it’s do NOT screw around with black holes.

100 million light years from Earth lies a galaxy called NGC 5813. It’s part of a small galaxy group, a collection of a few dozen other galaxies. When viewed in visible light NGC 5813 looks like any other elliptical galaxy: An elongated puffball with a few hundred billion stars in it.

But it has a supermassive black hole in its heart, one that tips the cosmic scales at 700 million times the mass ...