A team of astrophysicists have counted the number of starsblack hole mass in the observable universe to be 40 trillion, accounting for 1% of the total ordinary matter in the universe.
The researchers focused on stellar-mass black holes, the smallest known variety, but noted that their calculations could help solve a long-standing mystery of how supermassive black holes reproduce. Their research is published in the Astrophysics Journal Letter.
For a long time, black holes were only theorized to exist and were never observed—as their name suggests, black holes don’t let light escape their gravitational pull. But astronomers have discovered that black holes are at the center of large concentrations of light-emitting matter (our Milky Way has a supermassive black hole at its center). Recently, black hole mergers have been detected thanks to gravitational wave detectors such as the LIGO-Virgo Collaboration.
But counting all the black holes in the observable universe, which spans some 90 billion light years, is a daunting task. To reach the number 40 trillion (that’s 40 billion billion, or 40,000,000,000,000,000,000,000,000) the research team combined a new stellar evolution code called SEVN and with data on metals, star formation rates, and star sizes in known galaxies. .
“The innovative character of this work is to combine detailed models of stellar and binary evolution with advanced recipes for star formation and metal enrichment in individual galaxies,” said Alex Sicilia, astrophysicist at SISSA in Italy and lead author of the paper, at an institute. release. “This is one of the first, and one of the most robust, ab initio calculations of the mass function of a stellar black hole in cosmic history.”
The research is the first in a series of works that is attempting to model black hole masses, from star-sized to supermassive black holes. Star-mass black holes are the smallest known of their group, generally weighing a few to several hundred times the mass of the Sun. An intermediate black hole is famous absent From observational records, however, supermassive black holes are at the center of most galaxies and accrete matter around them, pulling stars, planets, and gas closer with their ridiculous gravitational forces.
In the paper, the researchers also investigated how black holes of various sizes could form. Star-mass black holes emerge from the cores of collapsing dead stars, but the origin of supermassive black holes is more of a mystery. Lumen Boco, also an astrophysicist at SISSA and a co-author of the paper, said in the same release that the team’s calculations “could be a starting point for investigating the origin of ‘heavy seeds’, which we will pursue in a future paper. ”
The new study does not address the so-called ancient black hole, a hypothetical object left over from the early universe that may be much smaller than any known black hole. There is no evidence that these actually exist, but some physicists have suggested them as potential solutions for dark matter mystery. One team actually proposed that a a black hole the size of a bowling ball could be Planet Nine, a theoretical object in the outer solar system orbiting a distant object.