How many black holes there are in the universe?
Since we do not see black holes, it is difficult to determine exactly how many such objects there are in the vast universe.
However, this does not mean that we should not try to find out.
Black holes in stellar mass are collapsed nuclei of dead massive stars; New research has explored how such stars and binary systems form and evolve, allowing us to re-evaluate the number of black holes in stellar mass in the universe.
The number is simply unimaginable: 40 quintiles, or 40,000,000,000,000,000,000,000 black holes, make up one percent of the normal matter of the observable universe.
“The innovative approach of this study lies in the detailed model of the evolution of stellar and dual systems and the pairing of advanced recipes for stellar formation and metal enrichment for each galaxy,” explains Alex Sicilia, an astrophysicist at the International School for Advanced Study in Italy (SISSA).
According to him, this is one of the first and most solid calculations in the entire cosmic history about the mass function of stellar black holes.
Black holes are one of the biggest puzzles in the universe for us. Many questions about them remain unanswered. If we knew approximately how many black holes there are in the universe, some questions might be answered.
One approach is to evaluate the history of massive stars in the universe. We will then be able to calculate the number of black holes in any given space.
Knowing this may even give us some clues as to the growth and evolution of supermassive black holes; Supermassive black holes lie at the center of galaxies and hold millions and billions of solar masses in them.
Sicily and his colleagues took a computer-based approach. Covered only those black holes that formed as a result of the evolution of the ellipse or double star; The role of black hole mergers, the number of which can be estimated based on gravitational wave data, was also considered. Such collisions result in slightly larger black holes.
As a result, they were able to calculate the birth rate of stellar black holes up to 5-160 solar masses during the existence of the universe.
This figure indicates that a black hole of about 40 quintillion stellar masses should be scattered in the observable universe; Among them, the most massive black holes of stellar mass are formed in star clusters, by merging double, that is, moving black holes around each other.
The data obtained the group compared with gravitational wave data and found that their estimates of black hole mergers were in good agreement with the observational data. This in turn indicates that the black hole collisions we have observed are most likely due to stellar collisions.
By calculating the birth rate over time, the researchers were also able to obtain quantitative estimates of black holes in stellar mass in the early universe. This is of great interest, because observations of the distant universe have already shown that soon after the Big Bang, supermassive black holes already existed.
It is unknown how these monsters were able to rise to such a large mass so suddenly. Scientists wonder if they grew from light stellar black holes or from heavier, intermediate-mass black holes.
A new study by the group will give us a basis for searching for these questions. This publication was at first the first in the whole series; To get a more complete picture of the distribution of black holes around the world, intermediate and supermassive black holes will be studied in the following studies.