by Researchers have discovered that invisible medium-sized black holes can form in dense star clusters containing thousands to millions of tightly packed stars known as “globular clusters.”
A medium-sized black hole has a mass between 100 and 10,000 suns. They are heavier than solar mass black holes, which have a mass range of 10 to 100 solar masses, but still lighter than supermassive black holes, which have masses equal to or even millions. billions the sun
Astronomers have been unable to find these cosmic interlopers, and the first example was found in 2012. Named GCIRS 13E, it has a mass 1,300 times that of the Sun and is located 26,000 light-years away, towards the galactic center of the Bull. Witness. Way.
One of the mysteries of medium-sized black holes concerns their formation. Supermassive black holes are born when massive stars collapse, and supermassive black holes grow from subsequent mergers of larger and larger black holes. However, a star massive enough to die and form a black hole with thousands of solar masses should be extremely rare and should struggle to maintain that mass when ” she is.”
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To investigate the mystery of these medium-sized black holes, a team of researchers conducted the first ever star-by-star simulation of massive clusters. This showed that a dense enough molecular cloud “birth nest” of globular clusters of stars could form massive enough to collapse and spawn a medium-sized black hole.
“Previous observations have suggested that some massive star clusters, globular clusters, host a medium-sized black hole,” team leader and University of Tokyo scientist Michiko Fujii said in a statement. “Until now, there has been no strong theoretical evidence showing the existence of a medium-sized black hole with 1,000 to 10,000 solar masses compared to smaller (stellar mass) and massive (supermassive) ones.”
Chaotic birthplace of black holes
The term “birth nest” might conjure up images and feelings of warmth, comfort and tranquility, but this could not be so appropriate for star formation in globular clusters.
These conglomerates of tightly packed stars live in chaos and turmoil, with differences in density causing collisions and mergers. That process results in stars accumulating mass, which increases their gravitational effects, pulling more stars into their vicinity, thus driving more and more mergers.
The process of collisions and mergers that take place in the core of globular clusters can create stars with masses equal to about 1,000 suns. That’s enough mass to create a medium-sized black hole, but there’s a hitch.
Astrophysicists know that when stars collapse to form black holes, supernova explosions or stellar winds remove much of their mass. Previous simulations of the creation of a medium-sized black hole have confirmed this, further suggesting that even massive stars with 1,000 solar masses would be too small to form a medium-sized black hole.
To determine whether a massive star could “live” with enough mass to give birth to a medium-sized black hole, Fujii and his team simulated a globular cluster as it formed.
“We have succeeded, for the first time, in numerical simulations of globular cluster formation, modeling individual stars,” said Fujii. “By solving individual stars with a realistic mass for each, we could recreate the collisions of stars in a tightly packed environment. For these simulations, we have developed a new simulation code in which we could integrate millions of stars with high precision.”
In the simulated globular cluster, collisions and runaway mergers created massive stars that could hold enough mass to collapse and give birth to a medium-sized black hole.
The team also found that the simulation predicted a mass ratio between the medium-sized black hole and the globular cluster in which it formed. That ratio, as it turns out, matches the actual astronomical observations.
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“Our ultimate goal is to simulate entire galaxies by resolving individual stars,” Fujii explained. “It is still difficult to simulate galaxies the size of the Milky Way by resolving individual stars using currently available supercomputers. However, smaller galaxies such as dwarf galaxies could be simulated.”
Fujii and her team plan to focus on the star clusters that formed early in the universe. “The first clusters are also places where medium-sized black holes can be born,” she said.
The team’s research was published Thursday (May 30) in the journal Science.
