Black hole can be described as the most terrifying of all celestial bodies, any matter close to it will be sucked in by its dark mouth, but the number of such celestial bodies in the universe is still quite large, there have been astronomers think that there are 1 million to 100 million black holes in the Milky Way alone, this number is quite amazing, we can also say that black holes in the Milky Way is also a large number of existence, fortunately so far has not found a black hole that is relatively close to the solar system, do not worry about the gravitational pull of the black hole to subvert the solar system.
So how many black holes are there in the universe? Perhaps many friends think how to study this? It should be a mystery that can never be known, but scientists have done research on this and estimated the approximate value of black holes in the observable universe, believing that the number of black holes in the universe is about 400 billion.
That's a scary number. The data was presented by an astronomy research team at the International Institute for Advanced Studies (SISSA) in Italy, spearheaded by astrophysicist Alex Sicilia, who "combined detailed models of star and binary evolution with advanced recipes for star formation and metal enrichment in individual galaxies," including "black holes formed by the evolution of single or binary stars, and taking into account the effects of black hole mergers, the number of which can be estimated from gravitational wave data and produce slightly more massive black holes." ”
Through these considerations, they calculated that the birth rate of stellar-mass black holes during the cosmic life cycle is 5 to 160 times the mass of the Sun, and believe that in today's observable universe, the total number of black holes may be as high as 400 billion, and its total mass accounts for about 1% of observable matter.
The team also compared their findings with observed gravitational wave data and found that their estimates of the number and rate of mergers of black holes were very consistent with the observational data. The study was published in the Astrophysical Journal in mid-January.
Black hole is a very magical celestial body, its mass can be very large, such as the central black hole of the Milky Way Sagittarius a* mass of up to 4.31 million times the mass of the Sun, while the central black hole of the Milky Way neighbor Andromeda Galaxy is 100 million times the Sun, the famous quasar Ton618 giant black hole has a mass of up to 66 billion times that of the Sun, but the largest known black hole is called SDSS J073739.96 +384413.2, and the mass is 104 billion times that of the Sun. Such black holes are usually the gravitational centers of a galaxy or giant type.
The universe has both massive giant black holes, there are also massive stellar black holes with similar masses to the sun, it is generally believed that there are stars formed, the least massive black hole is more than 3 times the mass of the sun, it is more than 30 times the mass of the sun when the star enters the terminal stage through the supernova explosion formed, but some more massive stars can collapse directly into black holes without going through the supernova explosion stage, and some black holes are formed by the collision of stars or neutron stars. Such stars typically have masses below 1,000 times the mass of the Sun.
However, astronomers believe that there are still some native black holes in the universe, these black holes were formed shortly after the birth of the universe, which was directly collapsed into the extremely dense material regions in the universe at that time, so that the black holes are large and small, basically all the galaxy center black holes and quasar black holes are such native black hole evolution, but such black holes can also be very small, even much smaller than the Earth, but this kind of black hole is only theoretically considered by astronomers to exist, and has not been actually observed.
At present, the number of black holes that have been observed by scientists and can be confirmed to exist is less than 100, and there is only one black hole that has been actually photographed by humans, which is the M87 central black hole 55 million light-years away, in order to observe it, scientists have used eight huge radio telescopes distributed around the earth to outline an observation device "as big as Earth", and it took several years to take and make pictures of this black hole.
But in fact, all humans can see is the accretion disk around this black hole, because the black hole itself is not luminous, so we can't see him, we can only think that it is hidden in the middle of the orange-yellow accretion disk in the middle of the void.
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Guangming Network January 20, 2022 article "How many black holes are there in the universe?" The latest figure is 400 billion