81 articles
3C 273
3C 273 is a quasar in the constellation Virgo, recognized in 1963 as the first quasar ever identified, with a jet about 300,000 light-years long and the power of thousands of galaxies.
3C 279
3C 279 is a flat-spectrum radio quasar in Virgo and a prototypical blazar, the first object in which apparent superluminal motion was detected, in 1971.
3C 286
3C 286, also known as J1331+3030 or B1328+307, is a compact steep-spectrum quasar at redshift 0.849, the Very Large Array's prime flux density calibrator for over half a century.
3C 345
3C 345 is a bright, variable blazar quasar in Hercules about 5.5 billion light-years away, a core-dominated superluminal radio source monitored optically since the 1960s.
3C 390.3
3C 390.3, also cataloged as B1845+797, is a nearby broad-line radio galaxy whose double-peaked emission lines come from an accretion disc around a supermassive black hole.
3C 454.3
3C 454.3, also cataloged as PKS 2251+158, is a flat-spectrum radio quasar, a type of blazar, in Pegasus at redshift 0.859 that repeatedly became the sky's brightest gamma-ray source.
3C 48
3C 48 is a radio-loud quasar, the 48th entry in the Third Cambridge Catalogue of radio sources, whose 1963 redshift of z = 0.37 helped solve the puzzle of the radio stars.
4C 11.69
4C 11.69, better known as the blazar CTA 102, is a flat-spectrum radio quasar whose 2016 outburst made it briefly the brightest gamma-ray source in the sky.
8C 0716+714
S5 0716+714, also known as 8C 0716+714, is a BL Lacertae object, a type of blazar, in the constellation Camelopardalis. Discovered in 1979, it is known for strong variability.
Active galactic nucleus
An active galactic nucleus (AGN) is a galaxy's bright central region, powered by gas and dust falling into a black hole millions to billions of solar masses.
AGN feedback
AGN feedback is the process by which energy and jets from an active supermassive black hole heat or eject gas in its host galaxy, quenching star formation.
AO 0235+164
AO 0235+164, also written 0235+164, is a highly variable blazar at redshift 0.94, classified as a BL Lac object, known for major flares including an October 2008 optical peak.
Baldwin effect
The Baldwin effect is the anticorrelation in quasars and active galactic nuclei where emission lines weaken as continuum luminosity rises, first reported by Jack Baldwin in 1977.
BL Lacertae
BL Lacertae (BL Lac) is the prototype blazar, an active galactic nucleus whose jet points almost at Earth. It was mistaken for a variable star when found in 1929.
BL Lacertae object
A BL Lacertae object (BL Lac, or BLL) is an active galactic nucleus with weak or no emission lines, one of the two blazar classes, named after BL Lacertae.
Black hole feedback
Black hole feedback is the transfer of energy from an accreting supermassive black hole to gas in its host galaxy, altering star formation and black hole growth.
Blazar
A blazar is an active galactic nucleus whose relativistic jet points almost directly at Earth, making it the most numerous identified gamma-ray source in the sky.
Broad absorption line quasar
A broad absorption line quasar is a quasar whose ultraviolet spectrum shows broad absorption troughs from fast gas outflows, about 10 to 15 percent of optically selected quasars.
Broad-line region
The broad-line region is the zone of dense gas a few light-days from an active galactic nucleus's supermassive black hole, producing broad emission lines used to measure black hole masses.
Centaurus A
Centaurus A, also designated NGC 5128, is a giant elliptical galaxy about 11 million light-years away and the nearest radio galaxy, containing the closest active galactic nucleus to Earth.
Changing-look AGN
A changing-look AGN is an active galactic nucleus whose broad emission lines appear or disappear within months to years, switching it between Type 1 and Type 2.
Circinus Galaxy
The Circinus Galaxy is a spiral galaxy about 13 million light-years from Earth, discovered in 1977 and hosting the nearest known Seyfert type 2 nucleus.
Damped Lyman-alpha systems
Damped Lyman-alpha systems (DLAs) are quasar absorption-line systems with neutral hydrogen column densities above 2 × 10²⁰ cm⁻², used to probe galaxy formation and chemical evolution.
Dual quasar
A dual quasar is a pair of quasars powered by two different supermassive black holes, shining simultaneously in a single merging galaxy system, typically separated by kiloparsecs.
Dusty torus
A dusty torus is an optically thick distribution of dust around the accretion disk and supermassive black hole of an active galactic nucleus, re-emitting absorbed radiation in the infrared.
E1821+643
E1821+643, also cataloged as H1821+643, is a luminous radio-quiet quasar about 3.4 billion light-years away in Draco, hosted by a giant elliptical galaxy at the center of a rich cluster.
Flat-spectrum radio quasar
A flat-spectrum radio quasar (FSRQ) is a blazar whose relativistic jet points near our line of sight, distinguished from BL Lac objects by strong, broad emission lines.
High-redshift quasar
A high-redshift quasar is a quasar, an active nucleus powered by a supermassive black hole, seen at redshift z above 6, within the Universe's first billion years.
Large quasar group
A large quasar group is a grouping of quasars closely matched in redshift and position, implying a larger dimmer structure; the Huge-LQG was the largest known structure in 2013.
Low-luminosity AGN
A low-luminosity active galactic nucleus (LLAGN) is a weak active galactic nucleus whose X-ray output falls below 10^42 erg/s, the most numerous AGN in the local Universe.