Primordial black hole

Primordial black hole

A primordial black hole is a hypothetical type of black hole that is formed not by the gravitational collapse of a star but by the extreme density of matter present during the universe's early expansion.

According to the Big Bang Model (also called the Standard Model), during the first few moments after the Big Bang, pressure and temperature were extremely great. Under these conditions, simple fluctuations in the density of matter may have resulted in local regions dense enough to create black holes. Although most regions of high density would be quickly dispersed by the expansion of the universe, a primordial black hole would be stable, persisting to the present.

Possible detection

One way to detect primordial black holes is by their Hawking radiation. Stephen Hawking theorized in 1974 that large numbers of such smaller primordial black holes might exist in the Milky Way in our galaxy's Halo region. All black holes are believed by many theorists to emit Hawking radiation at a rate inversely proportional to their mass. Since this emission further decreases their mass, black holes with very small mass would experience runaway evaporation, creating a massive burst of radiation at the final phase, equivalent to a nuclear weapon exploding. A regular black hole (of about 3 solar masses) cannot lose all of its mass within the lifetime of the universe (they would take about 1060 years to do so, even without any matter falling in). However, since primordial black holes are not formed by stellar core collapse, they may be of any size. A black hole with a mass of about 1012 kg would have a lifetime about equal to the age of the universe. If such low-mass black holes were created in sufficient number in the Big Bang, we should be able to observe some of those that are relatively nearby in our own Milky Way galaxy exploding today. NASA's GLAST satellite, launched in June 2008, is designed in part to search for such evaporating primordial black holes. However, if theoretical Hawking radiation does not actually exist, such primordial black holes would be extremely difficult, if not impossible, to detect in space due to their small size and lack of large gravitational influence. It has been suggested [I. B. Khriplovich, A. A. Pomeransky, N. Produit and G. Yu. Ruban, "Can one detect passage of small black hole through the Earth?", [ preprint] ] [I. B. Khriplovich, A. A. Pomeransky, N. Produit and G. Yu. Ruban, "Passage of small black hole through the Earth. Is it detectable?", [ preprint] ] that a small black hole passing through the Earth would produce a detectable acoustic signal. Because of its tiny diameter, large mass compared to a nucleon, and relatively high speed (~0.5 "c"), such primordial black holes would simply transit earth virtually unimpeded with only a few impacts on nucleons, exiting the planet with no ill effects.


The evaporation of primordial black holes has been suggested as one possible explanation for gamma ray bursts. This explanation is, however, considered unlikely. Other problems for which primordial black holes have been suggested as a solution include the dark matter problem, the cosmological domain wall problem [cite journal | author = D. Stojkovic | coauthors = K. Freese and G. D. Starkman | title = Holes in the walls: primordial black holes as a solution to the cosmological domain wall problem | journal = Phys. Rev. D | volume = 72 | page = 045012 | year = 2005 | url = | doi = 10.1103/PhysRevD.72.045012 | pages = 045012 [ preprint] ] and the cosmological monopole problem. [cite journal | author = D. Stojkovic | coauthors = K. Freese | title = A black hole solution to the cosmological monopole problem | journal = Phys. Lett. B | volume = 606 | pages = 251–257 | year = 2005 | doi = 10.1016/j.physletb.2004.12.019 [ preprint] ]

Even if they do not solve these problems, the low number of primordial black holes (they have never been verifiably detected) aids cosmologists by putting constraints on the spectrum of density fluctuations in the early universe.

String theory

General relativity predicts the smallest primordial black holes would have evaporated by now, but if there were a fourth spatial dimension — as predicted by string theory — it would affect how gravity acts on small scales and "slow down the evaporation quite substantially." [McKee, Maggie. (2006) [ – Satellite could open door on extra dimension] ] This could mean there are several thousand black holes in our galaxy. To test this theory scientists will use the Fermi Gamma-ray Space Telescope which was put in orbit by NASA on June 11, 2008. If they observe specific small interference patterns within gamma-ray bursts; it could be the first indirect evidence for primordial black holes and string theory.


* S.W. Hawking, [ Commun.Math. Phys. 43 (1975) 199] : the article it all began with !
* D. Page, [ Phys. Rev. D13 (1976) 198] : first detailed studies of the evaporation mechanism
* B.J. Carr & S.W. Hawking, [ Mon. Not. Roy. Astron. Soc 168 (1974) 399] : links between primordial black holes and the early universe
* A. Barrau et al., [ Astron. Astrophys. 388 (2002) 676] , [ Astron. Astrophys. 398 (2003) 403] , [ Astrophys. J. 630 (2005) 1015] : experimental searches for primordial black holes thanks to the emitted antimatter
* A. Barrau & G. Boudoul, [ Review talk given at the International Conference on Theoretical Physics TH2002] : cosmology with primordial black holes
* A. Barrau & J. Grain, [, Phys. Lett. B 584 (2004) 114] : searches for new physics (quantum gravity) with primordial black holes
* P. Kanti, [, Int. J. Mod. Phys. A19 (2004) 4899] : evaporating black holes and extra-dimensions

See also

Wikimedia Foundation. 2010.

Нужна курсовая?

Look at other dictionaries:

  • Black hole — For other uses, see Black hole (disambiguation). Simulated view of a black hole (center) in front of the Large Magellanic Cloud. Note the gravitat …   Wikipedia

  • Micro black hole — MBH redirects here. For other uses see MBH (disambiguation) Micro black holes are tiny black holes, also called quantum mechanical black holes or mini black holes, for which quantum mechanical effects play an important role.[1] It is possible… …   Wikipedia

  • Stellar black hole — A stellar black hole is a black hole formed by the gravitational collapse of a massive star (20 or more solar masses, though the exact amount of mass needed has not been determined and may depend on many parameters) at the end of its lifetime.… …   Wikipedia

  • Charged black hole — A charged black hole is a black hole that possesses electric charge. Since the electromagnetic repulsion in compressing an electrically charged mass is dramatically greater than the gravitational attraction (by about 40 orders of magnitude), it… …   Wikipedia

  • black hole — Astron. a theoretical massive object, formed at the beginning of the universe or by the gravitational collapse of a star exploding as a supernova, whose gravitational field is so intense that no electromagnetic radiation can escape. * * * Cosmic… …   Universalium

  • Black Hole — 1. Also called Black Hole of Calcutta. a small prison cell in Fort William, Calcutta, in which, in 1756, Indians are said to have imprisoned 146 Europeans, only 23 of whom were alive the following morning. 2. (l.c.) any usually wretched place of… …   Universalium

  • Nonsingular black hole models — A nonsingular black hole model is a mathematical theory of black holes that avoids certain theoretical problems with the standard black hole model, including information loss and the unobservable nature of the black hole event horizon. Contents 1 …   Wikipedia

  • Hole in the Sky festival — Hole in the Sky Kreator en Hole in the Sky 2007. Duración 2000−presente Localización Bergen, Noruega …   Wikipedia Español

  • Formation and evolution of black holes — From the exotic nature of black holes, it is natural to question if such bizarre objects could actually exist in nature or that they are merely pathological solutions to Einstein s equations. However in 1970, Hawking and Penrose proved the… …   Wikipedia

  • Hawking radiation — is a thermal radiation with a black body spectrum predicted to be emitted by black holes due to quantum effects. It is named after the physicist Stephen Hawking, who provided a theoretical argument for its existence in 1974, and sometimes also… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”