Scientists estimate the number of black holes in the universe at 40 trillion

Researchers have suggested research paper A new method, published in The Astrophysical Journal, presents a new method for calculating the number of black holes in the universe.

The study was carried out by an international scientific team of scientists led by The International School of Advanced Studies (SISSA) in Italy, according to a report The new method relied on studying stellar-mass black holes, which are the end of life for massive stars and have masses ranging from a few hundred times the mass of the Sun, that collapsed and died in those locations.

The researchers found that in the visible universe – which is a ball with a diameter of about 90 billion light-years – the number of black holes in it is about 40 trillion, or 40 billion billion, which represents 1% of the natural mass of the visible universe.

Black holes represent a huge question mark hanging in our understanding of the universe (Getty Images)

Can black holes be counted in the universe?

Black holes represent a huge question mark hanging in our understanding of the universe, or rather a lot of question marks, but if we have a good idea of ​​how many black holes there are, it may help answer some of these questions.

According to the available information, a black hole is a region in space with an enormous density (that is, it contains an extremely large mass for its size) often exceeding one million solar masses. The black hole also enjoys its high gravity as well, as it has the ability to swallow all the material surrounding it, and because of this very high gravity, even light cannot escape from it, and that is why it is called a black hole.

Since we cannot see black holes, it is difficult to know exactly how many holes there are in the large, vast universe, and trying to count black holes in the universe is like trying to count grains of sand in the desert.

Nevertheless, the scientists tried to find numbers in the new way that was found by a doctoral student at the International School of Advanced Studies Alex Cecilia and colleagues, led by Professor Andrea Labbe, Dr. Lumen Bocco and others.

Illustration of two black holes orbiting each other in a combined accretion disc. Eventually the black holes will merge, an event that will produce gravitational waves. Gravity is the distortion of space-time by mass, and changes in this distortion travel in waves at the speed of light. The effect is most pronounced where extremely massive objects are subject to extremely high acceleration. This is seen, for instance, where black holes or neutron stars are in a close orbit such as this. In February 2016, gravitational waves were detected for the first time, 100 years after Einsteins prediction. The waves emanated from the collision of two black holes, of 36 and 29 solar masses, some 1.3 billion light years away. The waves were extremely faint by the time they arrived at Earth, where they were detected by the two LIGO detectors in the USA.Trying to count the black holes in the universe is like trying to count the grains of sand in the desert (Getty Images)

How did researchers come to calculate black holes?

According to the study’s first author, Alex Cecilia – who included it Press release For the International School of Advanced Studies – he said that they were able to calculate the numbers of black holes in the visible universe by tracking the evolution of stars in the universe, and estimated the number of times that stars – whether alone or in binary systems – turn into black holes.

In order to achieve this, the researchers designed a model that simulates the evolution of galaxies over billions of years to find out the number of dead giant stars, and thus estimate the number of black holes left behind. When designing this model, the researchers took into account several factors, including: the fact that some galaxies can form new stars periodically, while other galaxies are unable to do so.

In addition to the “metallicity” of the galaxy, which is a measure that determines the amount of elements present inside each galaxy – except for hydrogen and helium – as the presence of a greater amount of metals can enhance the cooling of the gases in the galaxy, which helps galaxies to produce new stars effectively.

Researchers designed a model that simulates the evolution of galaxies over billions of years (French)

In order to track the evolution of these stars, and most importantly after their death, the researchers used known data from different galaxies in designing the model. such as their sizes, the elements they contain, and the sizes of gaseous clouds in which stars may form; Thus, the team built a model of the universe that accurately reflects the different sizes of stars that are formed, and how often they are created. These models showed scientists the percentage of stars in the galaxy that die annually.

Next, the researchers studied black holes that form through the evolution of single or binary stars, taking into account the role of black hole merging, whose numbers can be estimated based on gravitational wave data, which produces black holes with slightly higher masses.

The research team found that the largest stellar-mass black holes usually form from collisions of smaller black holes within star clusters, an idea that matches well with gravitational wave data collected so far about black hole collisions.

Black Hole, digital illustration - stock photoScientists hope the research results will provide a basis for investigating black hole exploration questions (Getty Images)

Towards a better understanding of the genesis of black holes

The “Science Alert” report says that it is not clear how these giant holes grew so quickly, as some current questions relate to the mass of the black hole “seeds” that they originated from, whether they are black holes with light stellar mass or medium-mass black holes.

Thus, scientists hope that the results of the research will provide a basis for investigating these questions, and this paper is the first in a series of research to explore black holes, and future papers will look at medium-mass black holes and supermassive black holes, to obtain a more complete picture of the distribution of black holes across the universe.

Astrophysicists hope to use the new estimate to investigate some of the vexing questions that arise from observations of the very early universe. For example, how the early universe became inhabited very quickly by supermassive black holes, shortly after the Big Bang.

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