This correlation is the most important thing we've learned about supermassive black hole so far. Astronomers are always looking for correlations. Whenever you find one that's really tight like this one, it's a sign that there is some basic physics there that you need to look for.

As it happens, the physics that might explain what was going on had been suggested years before by theorists Martin Rees and Jo Silk. Jo Silk has spent much of his life trying to solve the mystery of galaxy formation. Three years ago it became clear that he had been missing a vital ingredient. If there was a black hole in every galaxy, then scientists would need to explain what it was doing there.

We had to rethink our ideas of how galaxies were made. To understand the first light at(of/in) the universe we really have to include the role of the supermassive black holes in galaxy formation.

All previous ideas of galaxy formation had assumed that gas in the early universe simply condensed to form stars in galaxies. Silk and Rees came up with a completely different idea. They proposed that the center of each early gas cloud could have collapsed to form a giant black hole. The black hole would immediately start feeding on the gas around it creating a brilliant quasar.

correlation: a mutual relationship of interdependence between two or more things