active galactic nucleus

Small region at the centre of a galaxy that emits a prodigious amount of energy in the form of radio, optical, X-ray, or gamma radiation or high-speed particle jets. Many classes of “active galaxies” have been identified; they appear similar in many respects to quasars. Astronomers suspect that the observed energy is generated as matter accretes onto a supermassive black hole with a mass millions or even billions of times that of the Sun. The accreting matter can outshine the rest of the galaxy as it is heated in very high-speed collisions outside the black hole's event horizon. It is believed that many galaxies harbour these central black holes and that they might have been quasars in their early history, although they now appear to be dormant unless orbiting matter is accreting onto the black hole.

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.

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No references found	Other observations have revealed that NGC 4945 has an active galactic nucleus, meaning its central bulge emits far more energy than calmer galaxies like the Milky Way. New Images of Milky Way's Cousin Released by FARS News Agency Each such area is known as an active galactic nucleus (called AGN). High-energy discovery by Sohn, Emily / Science News for Kids Any bright galactic core not powered by starlight is known as an active galactic nucleus. Probing the heart of extragalactic jets by Cowen, Ron / Science News	active chaff Active Channel active chat active communications satellite active component active computer active content active controls technology active current active DBMS Active Desktop active detection system active device Active Directory Active Directory server active display active door active earth pressure active electric network active electronic countermeasures active element active entry active file active filter active front active galactic nucleus active galaxy active glacier active homing active hub active illumination active immunity active immuno-gene therapy active immunotherapy active infrared detection system Active Ion Transport active jamming Active Language I active lateral pressure active layer active leaf active leg active location system active logic active margin active master file active master item active material active matrix active matrix display Active Measurement Project	Active Federal Commissioned Service Active Federal Service active file Active File Set Active File Table Active filter Active Filter Media Active Final Approach Spacing Tool active fixation lead Active Fleet Active Flow Active for Life Active Force User Active Format Descriptor Active Framework for Data Warehousing Active Frequency-Selective Surface active front Active Front End Active Front Steering Active Fuel Length Active Fuel Management Active fund management Active Fund of Knowledge of a Student Active galactic nuclei Active galactic nuclei active galactic nucleus Active galaxies Active galaxies Active galaxy Active galaxy Active Galaxy Nuclei Active Galaxy Nuclei Active galaxy nucleus Active galaxy nucleus Active Geological Fault Active Geophysical Rocket Experiment active giving active glacier Active Global Support Active Guard and Reserve Active Guard and Reserve Active Guard Reserve Management Information System Active Guard Reserve/Full-Time Support Active Guard/Reserve Entry Training Active Handling System Active Harmonic Filter Active Harmonic Load-Pull Active Head Restraint Active Healthy Living Active Heave Compensation Active heave compensator Active heave compensator Active Hemicellulose Compound Active Hexose Correlated Compound active homing active homing guidance

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Other observations have revealed that NGC 4945 has an active galactic nucleus, meaning its central bulge emits far more energy than calmer galaxies like the Milky Way.

New Images of Milky Way's Cousin Released by FARS News Agency

Each such area is known as an active galactic nucleus (called AGN).

High-energy discovery by Sohn, Emily / Science News for Kids

Any bright galactic core not powered by starlight is known as an active galactic nucleus.

Probing the heart of extragalactic jets by Cowen, Ron / Science News

active chaff

Active Channel

active chat

active communications satellite

active component

active computer

active content