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A quasar is an extremely luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosities thousands of times greater than that of a galaxy such as the Milky Way. Quasars are usually categorized as a subclass of the more general category of AGN. The redshifts of quasars are of cosmological origin.
A microquasar, a smaller version of a quasar, is a compact region surrounding a stellar black hole with a mass several times that of its companion star, observable in sufficient details, in our own or nearby galaxy. The matter being pulled from the companion star forms an accretion disk around the black hole. This accretion disk may become so hot, due to friction, that it begins to emit X-rays. The disk also projects narrow streams or "jets" of subatomic particles at near-light speed, generating a strong radio wave emission.
A supermassive black hole is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, including light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center. For example, the Milky Way galaxy has a supermassive black hole at its center, corresponding to the radio source Sagittarius A*. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.
Eleanor Margaret Burbidge, FRS (née Peachey; 12 August 1919 – 5 April 2020) was a British-American observational astronomer and astrophysicist. In the 1950s, she was one of the founders of stellar nucleosynthesis and was first author of the influential B2FH paper. During the 1960s and 1970s she worked on galaxy rotation curves and quasars, discovering the most distant astronomical object then known. In the 1980s and 1990s she helped develop and utilise the Faint Object Spectrograph on the Hubble Space Telescope. Burbidge was also well known for her work opposing discrimination against women in astronomy while also opposing positive discrimination.
A dark galaxy is a hypothesized galaxy with no stars. They received their name because they have no visible stars but may be detectable if they contain significant amounts of gas. Astronomers have long theorized the existence of dark galaxies, but there are no confirmed examples to date. Dark galaxies are distinct from intergalactic gas clouds caused by galactic tidal interactions, since these gas clouds do not contain dark matter, so they do not technically qualify as galaxies. Distinguishing between intergalactic gas clouds and galaxies is difficult; most candidate dark galaxies turn out to be tidal gas clouds. The best candidate dark galaxies to date include HI1225+01, AGC229385, and numerous gas clouds detected in studies of quasars.
An optically violent variable quasar is a type of highly variable quasar. It is a subtype of blazar that consists of a few rare, bright radio galaxies, whose visible light output can change by 50% in a day. OVV quasars have essentially become unified with highly polarized quasars (HPQ), core-dominated quasars (CDQ), and flat-spectrum radio quasars (FSRQ). Different terms are used but the term FSRQ is gaining popularity effectively making the other terms archaic.
Phyla-Vell is a character appearing in American comic books published by Marvel Comics. Created by Peter David and Paul Azaceta, the character first appeared in Captain Marvel vol. 5 #16. Phyla-Vell is the daughter of superhero Mar-Vell and the sister of Genis-Vell. The character has also been known as Quasar, Captain Marvel, and Martyr at various points in her history.
Guinevere Alice Mei-Ing Kauffmann was born in California. She is an astrophysicist and is known for her work studying galaxies among other subjects.
Simon David Manton White, FRS, is a British-German astrophysicist. He was one of directors at the Max Planck Institute for Astrophysics before his retirement in late 2019.
Françoise Combes is a French astrophysicist at the Paris Observatory and a professor at the Collège de France where she has been the chair of Galaxies and cosmology since 2014.
Priyamvada (Priya) Natarajan is a theoretical astrophysicist and professor in the departments of astronomy and physics at Yale University. She is noted for her work in mapping dark matter and dark energy, particularly in gravitational lensing and in models describing the assembly and accretion histories of supermassive black holes. She authored the book Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos. She has been featured on shows such as Black Hole Apocalypse on PBS, showcasing her work and background.
Wendy Laurel Freedman is a Canadian-American astronomer, best known for her measurement of the Hubble constant, and as director of the Carnegie Observatories in Pasadena, California, and Las Campanas, Chile. She is now the John & Marion Sullivan University Professor of Astronomy and Astrophysics at the University of Chicago. Her principal research interests are in observational cosmology, focusing on measuring both the current and past expansion rates of the universe, and on understanding if there is missing physics in the standard cosmological model.
Green bean galaxies (GBGs) are very rare astronomical objects that are thought to be quasar ionization echos. They were discovered by Mischa Schirmer and colleagues R. Diaz, K. Holhjem, N.A. Levenson, and C. Winge. The authors report the discovery of a sample of Seyfert-2 galaxies with ultra-luminous galaxy-wide narrow-line regions (NLRs) at redshifts z=0.2–0.6.
Neta Bahcall is an Israeli astrophysicist and cosmologist specializing in dark matter, the structure of the universe, quasars, and the formation of galaxies.
TON 618 is a hyperluminous, broad-absorption-line, radio-loud quasar, and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It possesses one of the most massive black holes ever found, at 40.7 billion M☉.
NGC 585 is a spiral galaxy in the constellation of Cetus, which is about 245 million light-years from the Milky Way's center. The object was discovered on December 20, 1827, by the British astronomer John Frederick William Herschel.
Dara J. Norman is an astronomer and the deputy director of the Community Science and Data Center at the National Science Foundation's National Optical-Infrared Astronomy Research Laboratory (NOIRLab) in Tucson, Arizona. She is also the Association of Universities for Research in Astronomy Diversity Advocate at NOAO. Her research centers on the influence of Active Galactic Nuclei (AGN) on the evolution of galaxies. In 2020, she was inducted into the inaugural cohort of American Astronomical Society Fellows in recognition of her leadership and achievements.
4C +09.17 is a quasar located in the constellation Orion. With a redshift of 2.108300, the object is located 10.6 billion light years from Earth and presents an extragalactic astrophysical jet morphology.
References
- 1 2 academic.oup.com https://academic.oup.com/mnras/article/528/4/7376/7610919 . Retrieved 2024-05-14.
{{cite web}}: Missing or empty|title=(help) - 1 2 "Cold Quasars". kirkpatrick.ku.edu. Retrieved 2024-05-14.
- ↑ "AAS 234 Press Conference: Cold Quasars & Hot Cosmology". AAS Press Office via YouTube. 12 June 2019. Retrieved 13 June 2019.
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