The University of Colorado's Julie Comerford reported her findings today at the American Astronomical Society's annual meeting in Kissimmee (kuh-SIMM-ee) Florida.
Comerford says only 12 galaxies are known to exist with two black holes in their midst. Normally galaxies have a single supermassive black hole at the center.
But in this newly identified galaxy about 1 billion light-years away, one of the two black holes is smaller than the other and apparently starved of stars.
Comerford speculates the slim black hole either lost mass in the collision of two galaxies that merged into this one - a crash diet. Or it's a rare example of an intermediate-sized black hole that will grow.