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Space: About 40,000,000,000,000,000,000,000 black holes make up 1% of the observable universe

Have you ever wondered how many black holes there are? 40,000,000,000,000,000,000 constitutes 1% of the observable universe, study estimates

  • This calculation comes from the International School of Advanced Studies, Italy
  • They included data on properties such as stellar evolution and rates of formation
  • The finding could help us better understand the evolution of supermassive gaps

The observable universe contains 40,000,000,000,000,000,000 black holes in the mass of stars - that is 40 quintillion or 40 billion billion, a study has estimated.

Star mass black holes are those that form at the end of the life of giant stars and have masses between a few and a few hundred times that of the Sun.

Experts from the International School for Advanced Studies (SISSA) used a new calculation method to estimate how many of these gaps should have formed.

Moreover, they said that these black holes account for 1 percent of all the common, or 'baryonic', matter in the observable universe, which is 93 billion light-years across.

The results, the team said, pave the way for a better understanding of how black holes with stars and interstices can evolve into supermassive black holes.

The observable universe contains 40,000,000,000,000,000,000,000 black holes with star mass - that is 40 quintillion or 40 billion billion, a study has estimated.  Pictured: a simulated image of a black hole in front of the large Magellanic cloud

The observable universe contains 40,000,000,000,000,000,000 black holes in the mass of stars - that is 40 quintillion or 40 billion billion, a study has estimated. Pictured: a simulated image of a black hole in front of the large Magellanic cloud


In their study, astrophysicist Alex Sicilia and his colleagues calculated the number of black holes in the mass of stars, not in the entire universe - but the 'observable' part.

This is the spherical region, centered around the Earth, bounded by the farthest distances we could potentially see with our Earth and space telescopes, given the speed of light and the time that has elapsed since cosmological expansion.

Beyond this boundary - called the 'particle horizon' - nothing can be detected. The observable universe is currently about 93 billion light-years in diameter.

The calculation was made by the theoretical astrophysicist Alex Sicilia from Trieste, Italy-based SISSA and his colleagues.

"The innovative nature of this work lies in the coupling of a detailed model of stellar and binary evolution with advanced recipes for star formation and metal enrichment in individual galaxies," explained Mr. Sicily.

"This is one of the first and one of the most robust" ab initio " [from first principles] calculating the mass function of the star's black hole across cosmic history. '

To calculate their estimate of the number of black holes in the observable universe, the team combined models of how single and double star pairs evolve - and thus how many turn into black holes - with data on other relevant galactic properties.

The latter included information about star formation rates, star masses, and the metallicity of the interstellar medium - all of which influence the formation of black holes with star mass. They also took into account the role of black hole fusions.

From this, the team was also able to calculate the mass distribution of these black holes over the entire history of the observable universe.

In addition to estimating the total number of black holes with stellar mass in the observable universe, the researchers also explored different routes by which black holes with different masses can be formed.

This included looking at potential origins in isolated stars, binary star systems and more populous star clusters.

The team found that the largest black holes with star mass are typically formed from the collision of smaller black holes in star clusters - a notion that matches well the observational data from gravitational waves about black hole collisions collected to date.

'Our work provides a robust theory for light generation [stellar-mass] seeds for (super) massive black holes at high redshift, "said paper author and astrophysicist Lumen Boco, also from SISSA.

Thus, he added, 'may constitute a starting point for investigating the origin of "heavy seeds" [intermediate-mass black holes], which we will pursue in a future paper. '

In fact, with this initial study completed, researchers are now seeking to make similar calculations focused instead on medium-sized black holes and then, subsequently, their supermassive counterparts.

The full results of the study were published in The Astrophysical Journal.


Black holes are so dense and their gravity is so strong that no kind of radiation can escape them - not even light.

They act as intense sources of gravity that suck up dust and gas around them. Their intense gravity is thought to be what stars in galaxies orbit.

How they are formed is still poorly understood. Astronomers believe that they can form when a large cloud of gas up to 100,000 times larger than the sun collapses into a black hole.

Many of these black hole seeds then fuse together to form much larger supermassive black holes, which are found in the center of any known massive galaxy.

Alternatively, the seeds of a supermassive black hole could come from a giant star, about 100 times the mass of the sun, which eventually forms into a black hole after it runs out of fuel and collapses.

When these giant stars die, they also go into 'supernova', a huge explosion that displaces matter from the star's outer layer into deep space.



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