active galactic nucleus

(redirected from Active galaxies)
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Related to Active galaxies: Quasars

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 ?
All of these objects would later be understood to be active galaxies viewed in different orientations.
Some 10 percent of quasars and active galaxies emit such jets, which extend in opposite directions up to thousands of light-years.
VSOP will be looking at two main groups of radio sources: active galaxies and masers.
Observable properties of disc galaxies (including advances in the studies of galaxies, stellar discs of planar galaxies, gas components of disc galaxies, large-scale structures in S-galaxies, active galaxies, statistical dependences for the parameters of the galaxies):
Supermassive black holes in the nuclei of active galaxies, such as NGC 5548, expel large amounts of matter through powerful winds of ionized gas.
Special types of distant active galaxies and their innermost central regions show extreme physical processes.
At the centers of some active galaxies, X-ray observations at wavelengths corresponding to those of fluorescent iron show that this radiation is being absorbed.
Material is in sections on the molecular ISM in ULIRGs and starbursts, the atomic ISM on large and small scales, molecular gas in bars and disks, megamasers in starburst galaxies, starburst and AGN activity, superwinds and stellar clusters, and starbursts and active galaxies at high redshifts.
The telescope WIRE (Wide-Field Infrared Explorer), set for launch on a Pegasus XL, will conduct a 4-month study of these highly active galaxies.
Ball Aerospace is currently teamed with the NASA Ames Research Center on a new mission concept, K2, that would continue Kepler's search for other worlds, and introduce new opportunities to observe star clusters, young and old stars, active galaxies and supernovae.
Next, data on galaxies surrounding active galaxies were gathered from galaxy catalogues of UKIDSS; the number of galaxies reached approximately 70 million.
ALMA's results reveal to us that there is little-to-no starbursting going on in these young, active galaxies.