From the May 2009 issue

When galaxies merge, what happens to their central black holes?

Ken Renner, Navarre, Ohio
By | Published: May 26, 2009 | Last updated on May 18, 2023
July 2009 black holes
Two black holes merge in this computer-generated image based on a NASA simulation. As the black holes approach each other, their violent interaction generates ripples in the fabric of space-time.
Chris Henze (NASA)

When galaxies merge, their central black holes combine to form a single, more massive black hole.