https://phys.org/news/2017-01-role-supermassive-black-holes-galaxies.html
In roughly four billion years, the Milky Way will be no more.
Indeed, our home galaxy is on course to collide and unite with the Andromeda Galaxy, at present some two million light years away.
Of course, we don't notice that the two galaxies are drawing closer together. "To the human perspective, our galaxy doesn't appear
to be changing," says University of Iowa astrophysicist Hai Fu, "but in the history of the universe, it is changing all the time."
Galaxies have been merging for most of the universe's 13-billion-year history, and scientists have been observing these mergers for
some time. What they don't fully understand is how mergers occur.
Fu, an assistant professor in physics and astronomy, aims to clarify the phenomenon by observing supermassive black holes (with a mass
of about one billion suns), which are at the center of most galaxies. Astrophysicists believe large galaxies grow by devouring smaller
ones. In such cases, the black holes of both are expected to orbit each other and eventually merge. Fu and his team won a three-year,
$405,011 grant from the National Science Foundation to find and characterize these celestial events.
