Black hole

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Blackness of space with black marked as center of donut of orange and red gases
The supermassive black hole at the core of supergiant elliptical galaxy Messier 87, with a mass ~7 billion times the Sun's,[1] as depicted in the first image released by the Event Horizon Telescope (10 April 2019).[2][3][4][5] Visible are the crescent-shaped emission ring and central shadow, which are gravitationally magnified views of the black hole's photon ring and the photon capture zone of its event horizon. The crescent shape arises from the black hole's rotation and relativistic beaming; the shadow is about 2.6 times the diameter of the event horizon.[3]

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A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it.[6] The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.[7][8] The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed.[9] In many ways, a black hole acts like an ideal black body, as it reflects no light.[10][11] Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.

Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace.[12] The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Black holes were long considered a mathematical curiosity; it was during the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars by Jocelyn Bell Burnell in 1967 sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.

Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses (Template:Solar mass) may form. There is general consensus that supermassive black holes exist in the centers of most galaxies.

Despite its invisible interior, the presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light. Matter that falls onto a black hole can form an external accretion disk heated by friction, forming some of the brightest objects in the universe. If there are other stars orbiting a black hole, their orbits can be used to determine the black hole's mass and location. Such observations can be used to exclude possible alternatives such as neutron stars. In this way, astronomers have identified numerous stellar black hole candidates in binary systems, and established that the radio source known as Sagittarius A*, at the core of the Milky Way galaxy, contains a supermassive black hole of about 4.3 million solar masses.

On 11 February 2016, the LIGO collaboration announced the first direct detection of gravitational waves, which also represented the first observation of a black hole merger.[13] As of December 2018, eleven gravitational wave events have been observed that originated from ten merging black holes (along with one binary neutron star merger).[14][15] On 10 April 2019, the first ever direct image of a black hole and its vicinity was published, following observations made by the Event Horizon Telescope in 2017 of the supermassive black hole in Messier 87's galactic centre.[3][16][17]

Schwarzschild black hole
Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the background
Gas cloud being ripped apart by black hole at the centre of the Milky Way (observations from 2006, 2010 and 2013 are shown in blue, green and red, respectively).[18]

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See also[edit]

  1. Oldham, L. J.; Auger, M. W. (March 2016). "Galaxy structure from multiple tracers – II. M87 from parsec to megaparsec scales". Monthly Notices of the Royal Astronomical Society. 457 (1): 421–439. arXiv:1601.01323. Bibcode:2016MNRAS.457..421O. doi:10.1093/mnras/stv2982.
  2. Overbye, Dennis (10 April 2019). "Black Hole Picture Revealed for the First Time – Astronomers at last have captured an image of the darkest entities in the cosmos – Comments". The New York Times. Retrieved 10 April 2019.
  3. 3.0 3.1 3.2 Event Horizon Telescope, The (2019). "First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole". The Astrophysical Journal. 87 (1). doi:10.3847/2041-8213/ab0ec7.
  4. Landau, Elizabeth (10 April 2019). "Black Hole Image Makes History". NASA. Retrieved 10 April 2019.
  5. Anon (11 April 2019). "The woman behind first black hole image". bbc.co.uk. BBC News.CS1 maint: date and year (link)
  6. Wald 1984, pp. 299–300
  7. Wald, R. M. (1997). "Gravitational Collapse and Cosmic Censorship". In Iyer, B. R.; Bhawal, B. (eds.). Black Holes, Gravitational Radiation and the Universe. Springer. pp. 69–86. arXiv:gr-qc/9710068. doi:10.1007/978-94-017-0934-7. ISBN 978-9401709347.
  8. Overbye, Dennis (8 June 2015). "Black Hole Hunters". NASA. Archived from the original on 9 June 2015. Retrieved 8 June 2015. Unknown parameter |deadurl= ignored (help)
  9. "Introduction to Black Holes". Retrieved 26 September 2017.
  10. Schutz, Bernard F. (2003). Gravity from the ground up. Cambridge University Press. p. 110. ISBN 978-0-521-45506-0. Archived from the original on 2 December 2016. Unknown parameter |deadurl= ignored (help)
  11. Davies, P. C. W. (1978). "Thermodynamics of Black Holes" (PDF). Reports on Progress in Physics. 41 (8): 1313–1355. Bibcode:1978RPPh...41.1313D. doi:10.1088/0034-4885/41/8/004. Archived from the original (PDF) on 10 May 2013. Unknown parameter |deadurl= ignored (help)CS1 maint: ref=harv (link)
  12. Cite error: Invalid <ref> tag; no text was provided for refs named origin
  13. Cite error: Invalid <ref> tag; no text was provided for refs named PRL-20160211
  14. Siegel, Ethan. "Five Surprising Truths About Black Holes From LIGO". Forbes. Retrieved 12 April 2019.
  15. "Detection of gravitational waves". LIGO. Retrieved 9 April 2018.
  16. Bouman, Katherine L.; Johnson, Michael D.; Zoran, Daniel; Fish, Vincent L.; Doeleman, Sheperd S.; Freeman, William T. (2016). "Computational Imaging for VLBI Image Reconstruction": 913–922. arXiv:1512.01413. doi:10.1109/CVPR.2016.105. hdl:1721.1/103077. Cite journal requires |journal= (help)
  17. Gardiner, Aidan (12 April 2018). "When a Black Hole Finally Reveals Itself, It Helps to Have Our Very Own Cosmic Reporter - Astronomers announced Wednesday that they had captured the first image of a black hole. The Times's Dennis Overbye answers readers' questions". The New York Times. Retrieved 15 April 2019.
  18. "Ripped Apart by a Black Hole". ESO Press Release. Archived from the original on 21 July 2013. Retrieved 19 July 2013. Unknown parameter |deadurl= ignored (help)