Active Galactic Nuclei and Supermassive Black Holes
Until recently, the underlying physics of active galactic nuclei (AGN) were somewhat of a mystery to cosmologists.
Active Galactic Nuclei
Many galaxies have very bright nuclei, so bright that the central region can be more luminous than the remaining galaxy light. These nuclei are called active galactic nuclei, or AGN for short.
Definition: active galactic nuclei (AGN): A class of galaxies which spew massive amounts of energy from their centers, far more than ordinary galaxies.
Active galactic nuclei (AGN) may be defined loosely as the central regions of galaxies which show substantial energy release beyond what can be attributed to normal processes from stars, ISM, and their interactions.
active galactic nuclei (AGN)
It is believed that these are normal galaxies with a massive black hole accreting gas at its center, thus producing enormous amounts of energy at all wavelengths of the electromagnetic spectrum.
Active Galactic Nuclei (AGN): A galaxy with an unusually bright central region thought to contain a supermassive black hole actively pulling in tremendous amounts of matter from a swirling disk of gas, stars, and dust.
active galactic nuclei
the exceptionally bright cores of some galaxies, thought to be fueled by matter falling into supermassive black holes
active galaxy ...
ACTIVE GALACTIC NUCLEI
Active galactic nuclei (AGN) are galaxies that have a massive black hole at the galactic center (nucleus). These galaxies produce huge amounts of energy (at all wavelengths of the electromagnetic spectrum).
ACTIVE GALACTIC NUCLEI
Books
Gaustad, John & Zeilik, Michael, Astronomy: The Cosmic Perspective- second edition, John Wiley & Sons, Inc., 1990.
Active galactic nuclei (25)
It is reasonable to suppose that the future holds many further improvements in both the quality and the availability of astronomical data and that many new discoveries will be made.
active galactic nuclei (AGN)
The centers of active galaxies that are emitting large amounts of excess energy.
active galaxy ...
Active galactic nuclei (AGN)
Blazar
List of quasars
Optically Violently Variable (OVV) quasars
Supermassive black hole
Microquasar ...
- active galactic nuclei (AGN) - Space and Astronomy Definition - Online Dictionary and Glossary Definition of active galactic nuclei (AGN)
- Flash Accessibility
- EVMS User Guide - Active and spare objects ...
Blazars are active galactic nuclei -- energetic regions surrounding massive black holes at the centers of galaxies. Material being drawn into the black hole forms a spinning disk called an accretion disk.
active galactic nuclei (High Energy Astrophysics Dictionary- GSFC) Normal galaxies with a massive black hole accreting gas at its center, thus producing enormous amounts of energy at all wavelengths of the electromagnetic spectrum.
Objects with a great variety of names - QSOs (or quasars), blazars, Seyfert galaxies, radio galaxies, and sometimes liners(low ionization nuclear emission line galaxies) - are all grouped into the category active galactic nuclei (AGN) because they ...
Other objects commonly observed in ultraviolet light include planetary nebulae, supernova remnants, and active galactic nuclei.
Previous surveys of so-called active galactic nuclei (AGN; the active black holes in the centres of galaxies) had only detected two percent in merging galaxies, ...
In the years since, astronomers realized that there is an explanation for these active galactic nuclei which is consistent with observations and with theory -- even though this explanation boggles the mind: at the core of these galaxies is a ...
These brilliant cores are called active galactic nuclei. Most of these objects are very distant, and the activity producing this radiation appears to be a stage in the early evolution of a galaxy.
Candidates for more massive black holes were first provided by the active galactic nuclei and quasars, discovered by radioastronomers in the 1960s.
In 1995, NASA orbited the Rossi X-ray Timing Explorer (RXTE) to study the variations in the emission of such X-ray sources as black-hole candidates, active galactic nuclei, white dwarf stars, neutron stars, and other high-energy sources.
In this view quasars are special Active Galactic Nuclei that have their jets lined up with our line of sight. So we are looking straight down the jet and it seems extraordinarily bright.
So, it is also termed the active galactic nuclei (AGN). We are not completely sure how an active galaxy is formed and how it generates such a large amount of energy. One of the most popular hypothesis is the supermassive black hole theory.
Utilized in a theoretical model for quasars and active galactic nuclei, according to which the energy source is due to infall (and resultant heating) of gas and stars onto a supermassive central black hole. [SILK90]
Massive Halos ...
Active Galactic Nucleus (AGN): The central region of an active galaxy where the energtic activity is concentrated. The active galactic nuclei are believed to contain supermassive black holes that power the nonstellar phenomena associated with active ...
In those cases, we may just refer to them as Active Galactic Nuclei. Either way, these are amongst the strangest things out there. Actually, about 10% of all galaxies are active, so you can't ignore them.
An object that releases energy. Commonly used to refer to the source of energy in active galactic nuclei
Epicycle ...
A black hole possessing as much mass as a million or a billion stars. Supermassive black holes reside in the centers of galaxies and are the engines that power active galactic nuclei and quasars.
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132. Energy Machine
An object that releases energy. Commonly used to refer to the source of energy in active galactic nuclei.
Active galactic nuclei are believed to contain supermassive black holes that power the nonstellar phenomena associated with active galaxies. Examples of active galaxies include: Seyfert galaxies, Radio galaxies (image), and BL Lac objects.
It was launched in February 1997 and is orbiting the Earth in an elliptical orbit to enable VLBI observations on baselines between space and ground telescopes. The primary targets are active galactic nuclei, water masers, OH masers, radio stars, ...
These may range in mass from about 106 to 109 solar masses. Such supermassive black holes are likely to be responsible for phenomena such as active galactic nuclei (AGNs), Seyfert galaxies, BL Lacerate Objects and quasars or QSOs.
galaxies were formed by violent gravitational encounters, like near-collisions of nearby galaxies. Examples of starburst galaxies include NGC 253 and the barred spiral galaxy NGC 1808. Starburst galaxies may be related to active galactic nuclei.
 See also: Galaxies, Energy, Ray, Light, Galaxy
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