active galactic nucleus

(redirected from Active galactic nuclei)
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Related to Active galactic nuclei: quasar

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 ?
ETH researchers discovered in their extensive data collection of observed active galactic nuclei that about 5 percent appeared to be in a 'switched-off' state.
The 89 papers reflect current understanding and ongoing controversy regarding active galactic nuclei (AGN), including the few that are loud in radio frequencies as well as bright in visible light.
According to ISRO, while operating from its 8[degrees] inclination in its 650km (400 miles) orbit Astrosat's scientific objectives include spectroscopic studies of X-ray binaries, supernova remnants, active galactic nuclei and galaxy clusters.
Johnson, whose field of study is active galactic nuclei, hopes to create an environment for prospective scientists that is every bit as stimulating as his own.
Designed to provide new insights into celestial objects such as black holes, neutron stars, active galactic nuclei and supernovae, the 2 tonne INTEGRAL vehicle is equipped with a payload that includes a spectrometer (known as the SPectrometer on INTEGRAL -- SF1), an imager (the Imager on Board the INTEGRAL Satellite -- IBIS), an X-Ray monitor (the Joint European X-ray Monitor -- JEM-X), an Optical Monitoring Camera (0MG) and an Integral Radiation Environment Monitor (IREM).
Current projects under his leadership include research on active galactic nuclei.
His Research interests are active galactic nuclei, galactic black-hole candidates and gamma-ray bursts.
This unified model said that the active nuclei in each type of galaxy were similar, but researchers are now proposing that the active galactic nuclei are actually different on a structural and energetic level.
It even rivals active galactic nuclei (AGN), which are powered by accreting supermassive black holes.
Recent cosmological simulations have demonstrated that ""feedback"" by star formation, supernovae and active galactic nuclei appears to be critical in obtaining realistic disk galaxies, to slow down star formation to the small observed rates, to move gas and metals out of galaxies into the intergalactic medium, and to balance radiative cooling of the low-entropy gas at the centers of galaxy clusters.