Active Galactic Nuclei

At the center of nearly every large galaxy lies a supermassive black hole, millions of times more massive than our Sun. Some of these black holes don’t just sit there quietly — they act like hungry cosmic sharks, gobbling gas and dust from their surroundings. As all this material spirals inward, it heats up and glows so brightly it can outshine all the stars in the galaxy combined. That blazing central region is called an active galactic nucleus, or AGN.

These cosmic powerhouses shine in every kind of light, from radio waves to visible light to X-rays, and sometimes they even send out other signals like neutrinos or cosmic rays. All that energy comes from matter falling toward the black hole and releasing radiation as it spirals inward. In other words, when a supermassive black hole is in the midst of a feeding frenzy, it lights up the galaxy’s center.

Rubin Observatory is transforming how we study active galactic nuclei by finding many more of them than ever before, including ones from the distant Universe whose light has taken billions of years to reach us. Rubin’s six filters will help scientists identify AGN from among billions of light sources. And Rubin won’t just find them, it will track their changes in brightness during its repeated scans of the sky, revealing their feeding patterns. Over its 10-year survey, Rubin is expected to find millions of active galactic nuclei across the Universe. Researchers are eagerly anticipating this enormous sample population of AGN, which they’ll use to estimate black hole masses and learn more about how galaxies and their central features evolve together.

Further exploration:

• Learn more about Rubin alerts

• See a sample AGN alert

• Check out how many varying AGN and other changes Rubin finds in just a single image