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phy_freak
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I need to know when did the first black holes appear?
Chronos said:Possibly before the first stars, but this is uncertain. They are difficult to detect save by gravitational effects on nearby objects, which obviously must be very luminous.
[. . .]the Royal Swedish Academy of Sciences awarded the 2012 Crafoord Prize in Astronomy to Reinhard Genzel and Andrea Ghez for their separate work on proving the existence of the supermassive black hole at the centre of our galaxy. [. . .]
http://www.eso.org/public/announcements/ann12006/
Observational work conducted over the past few decades indicates that all massive galaxies have supermassive black holes at their centres. Although the luminosities and brightness fluctuations of quasars in the early Universe suggest that some were powered by black holes with masses greater than 10 billion solar masses1, 2, the remnants of these objects have not been found in the nearby Universe.
[. . . ]
http://www.nature.com/nature/journal/v480/n7376/abs/nature10636.html
The concept of black holes was first proposed by John Michell in 1783 and independently by Pierre-Simon Laplace in 1796.
The first observed black hole was discovered in 1971 by physicist Stephen Hawking and astronomer John Wheeler.
Scientists first had evidence for the existence of black holes in the 1960s through observations of quasars, which are thought to be powered by supermassive black holes.
The first stellar-mass black hole was discovered in 1971 by physicist Stephen Hawking and astronomer John Wheeler.
The first observation of gravitational waves from a merger of two black holes was made in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) collaboration.