The average black hole expands at the same rate as its host galaxy. That’s not the case for a newly discovered super-sized black hole.

The find shocked astronomers who were looking for average black holes in average galaxies.

“Our survey was designed to observe the average objects, not the exotic ones,” said C. Megan Urry, Yale’s Israel Munson Professor of Astrophysics and co-author of the study. “This project specifically targeted moderate black holes that inhabit typical galaxies today. It was quite a shock to see such a ginormous black hole in such a deep field.”

Here’s what they found. The black hole, located in the galaxy CID-947, sits in the upper class of the most massive black holes ever discovered. Take nearly seven billion of our suns. That’s how massive this black hole is.

On any other day, this massive black hole would have been the surprise. But, what surprised astronomers most was the galaxy it was in.

“The measurements correspond to the mass of a typical galaxy,” said lead author Benny Trakhtenbrot, a researcher at ETH Zurich’s Institute for Astronomy. “We therefore have a gigantic black hole within a normal-size galaxy.”

What about the galaxy? CID-947 is still producing stars. Astronomers believe it could continue to grow, but that also means the black hole will continue to grow.

As for its future? CID-947 may be a precursor to a much more massive system. One day it could look more like NGC 1277, a galaxy located in the Perseus constellation. There has been some disagreement over the size of the black hole in NGC 1277, but it is believed to contain one of the most massive ever found. One study suggested its black hole has a mass of 17 billion solar masses.

The W.M. Keck Observatory was instrumental for the discovery.

“The sensitivity and versatility of Keck’s new infrared spectrometer, MOSFIRE, was critical to this discovery,” Urry said.

The W.M. Keck Observatory is one of the best telescopes in the world. It consists of two telescopes, each reaching eight stories into the sky and weighing a massive 300 tons. Each of the telescopes’ mirrors is 10 meters in diameter.


Its location atop Hawaii’s Mauna Kea volcano plays a vital role in astronomy observations. Light pollution is minimal and clear skies atop the dormant volcano allow for nearly year-round observations.

The MOSFIRE instrument Urry is talking about can image the most distant objects in our Universe. Here’s the very first image taken by W.M. Keck’s MOSFIRE instrument.

MOSFIRE first image

Astronomers can use the MOSFIRE instrument to see back in time to a period just 500 million years after the Big Bang.

Image credits: Top illustration by Michael S. Helfenbein, W.M. Keck Observatory