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active galaxy

British

noun

Also called: active galactic nucleus. a galaxy that emits usually large amounts of energy from a very compact central source, such as Seyfert galaxies, radio galaxies, and quasars

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

active galaxy Scientific

A galaxy emitting unusually high quantities of radiation from an active galactic nucleus at its center. Some active galaxies emit more energy in radio wavelengths than they do visible light. Seyfert galaxies are examples of active galaxies.
See more at galactic nucleus

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active galaxy

Blazars are a type of active galaxy powered by supermassive black holes that shoot out powerful, narrow jets of particles and radiation at nearly the speed of light.

From Science Daily ● Nov. 7, 2025

NGC 4945 is an active galaxy about 13 million light-years away in the southern constellation Centaurus.

From Science Daily ● Jan. 12, 2024

The detection of neutrinos ostensibly coming from this active galaxy is a big deal.

From Scientific American ● Dec. 20, 2022

“Where exactly in the active galaxy, the neutrinos are produced will be a matter of debate,” he added in an email.

From New York Times ● Jul. 12, 2018

Could the Milky Way ever become an active galaxy?

From Textbooks ● Oct. 13, 2016

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023