In the world of black holes, there are generally three size categories: stellar-mass black holes (about five to 50 times the mass of the sun), supermassive black holes (millions to billions of times the mass of the sun), and intermediate-mass black holes with masses somewhere in between.

In the world of black holes, there are generally three size categories: stellar-mass black holes (about five to 50 times the mass of the sun), supermassive black holes (millions to billions of times the mass of the sun), and intermediate-mass black holes with masses somewhere in between.

While we know that intermediate-mass black holes should exist, little is known about their origins or characteristics—they are considered the rare “missing links” in black hole evolution.