An Etymological Dictionary of Astronomy and Astrophysics
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An → accretion disk formed around a → black hole.

→ circum-; → black; → hole.

The outcome of a → merger process between two galaxies, each with its own central → supermassive black hole (SMBH), resulting in a remnant galaxy hosting two SMBHs. Simulations of → galaxy mergers show there should be lots of dual → active galactic nuclei (AGN) visible at less than 10 kpc separations. As of 2015 more than 100 known dual supermassive black holes have been found. See also → binary supermassive black hole.

→ dual; → supermassive; → black; → hole.

A → black hole with a mass in the range 10²-10⁴ solar masses. IMBHs may form as the result of multiple → mergers of smaller objects in the centers of dense stellar clusters in the present universe, assuming → mass loss from → stellar winds is not significant. They may also arise from the evolution of → very massive stars early in the history of the Universe, forming black hole "seeds" in the centers of massive halos (the precursors of the galaxies we see today) early in the history of the Universe, to redshifts z > 10. Currently the best observational evidence for IMBHs comes from models of ultraluminous X-ray sources (See, e.g., J. M. Centrella et al. 2010, astro-ph/1010.5260).

→ intermediate; → mass; → black; → hole.

A → black hole that possesses only mass (not electric charge) and rotates about a central axis. It has an → ergosphere and a → stationary limit.

Named after the New Zealand mathematician Roy P. Kerr (1934-) who, in 1963, was the first to solve the → field equationss of Einstein's theory of → general relativity for a situation of this kind; → black hole.

A rotating charged black hole. Compare with the → Kerr black hole and the → Reissner-Nordstrom black hole.

Named after Roy P. Kerr and Ezra T. Newman (1929-) who in 1963 independently found this solution to Einstein's → field equations; → black; → hole.

1a) Deficiency or absence of something needed, desirable, or customary.
1b) Something missing or needed. See also → default, → deficiency, → shortage.
2a) (v.tr.) To be without or deficient in; to fall short in respect of.
2b) (v.intr.) to be absent or missing, as something needed or desirable (Dictionary.com).

M.E. lak; cognate with M.L.G. lak, M.Du. lac "deficiency;" akin to O.Norse lakr "deficient."

Nast, from negation prefix na- "in-, non," → not, + ast, hast "is," from astan, hastan "to be," → exist.

Absent; wanting; deficient.

→ lack; → -ing.

A black hole with a mass between millions and billions of solar masses residing in galactic nuclei. The mass of this type of black holes represents about 0.2% of the bulge mass. When matter is swallowed by the black hole, this gives rise to the tremendous energetic phenomena observed in quasars and active galactic nuclei.

→ massive; → black hole.

A black hole of mass as low as 10^-6 gram supposed to have formed in the early Universe following the Big Bang event. Same as primordial black hole.

Mini a shortening of → minimum; → black hole.

A formula that determines the distribution of intensity of radiation that prevails under conditions of thermal equilibrium at a temperature T: B_v = (2hν³ / c²)[exp(hν / kT) - 1]^-1 where h is Planck's constant and ν is the frequency.

→ Planck; → blackbody; → formula.

A black hole formed following the Big Bang event due to incredibly violent turbulence that squeezed concentrations of matter to high densities. These black holes, first suggested by Stephen Hawking, are expected to have a mass comparable to that of a mountain and a size as small as an atom. Same as → mini black hole.

→ primordial; → black hole.

A type of electrically charged → black hole that is spherically symmetric and non-rotating. Another type of such objects is the → Kerr-Newman black hole.

Named after the German physicist Hans Jacob Reissner (1874-1967) in 1916 and the Finnish Gunnar Nordstrom (1881-1923) in 1918 independently worked out solutions different from those of Schwarzschild; → black hole.

A black hole that possesses angular momentum, as first postulated by Roy C. Kerr in 1963. Opposite of a stationary black hole. → ergosphere.

→ rotating; → black hole.

A → black hole with zero → angular momentum (non-rotating) and zero electric charge derived from Karl Schwarzschild 1916 exact solution to Einstein's vacuum → field equations.

Karl Schwarzschild (1873-1916), German mathematical physicist, who carried out the first relativistic study of black holes. → black hole.

The surface area of a black hole's horizon can never decrease.

→ second; → law; → black hole; → mechanics.

A → black hole with zero → angular momentum, that does not rotate.

→ stationary; → black hole.

A → black hole with a mass in the range 3-30 → solar masses representing the end-product of → massive star evolution. Since → neutron stars cannot have masses larger than 3 solar masses, compact objects more massive than this must be black holes. There is good observational evidence for the existence of stellar black holes, based in particular on dynamical measurements of the masses of compact objects in → transient X-ray sources. Same as → stellar-mass black hole.

→ stellar; → black; → hole.

Same as → stellar black hole.

→ stellar; → mass; → black; → hole.

A → black hole of tremendous mass, equivalent to those of millions or even billions of stars, which is believed to exist and occupy the centers of many galaxies. The supermassive black hole residing in the center of our → Milky Way Galaxy is the object → Sgr A* with a mass of 4 x 10⁶→ solar masses within a radius of 100 → astronomical units.

→ supermassive; → black hole.