active galactic nucleus


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active galactic nucleus

(AGN) See active galaxy.

active galactic nucleus

[¦ak·tiv gə‚lak·tik ′nü·klē·əs]
(astronomy)
A central region of a galaxy, a light-year or less in diameter, where violent and apparently explosive behavior is observed which is manifested in many ways, including the high-velocity outflow of gas, strong nonthermal radio emission, intense and often polarized and highly variable radiation over a wide range of wavelength bands, and ejection of jets of relativistic material.
References in periodicals archive ?
The resolution at which they were able to observe this highly luminescent active galactic nucleus (AGN) has given them direct confirmation of how mass accretes onto black holes in centres of galaxies.
Jaffe of the State University of Leiden in the Netherlands, the Hubble image provides the closest look yet at the center of a type of galaxy -- called an active galactic nucleus (AGN) -- that has a luminous, energetic core.
Theoretical models show that a merger is a great way to trigger an active galactic nucleus, because it funnels a lot of gas to the center of the galaxy.