Black holes in general are a kind of gigantic “monsters” that devour everything in their path. However, we know that there are different sizes and voracities. For example, those in the center of galaxies are usually supermassive black holes. The one of ours, called Sagittarius A, has a mass equivalent to 4 million soles. But there are bigger ones. And with more “hunger”. It is the case of J2157, what’s wrong with it 34 billion times the mass of the sun and gobbles up as much mass as our star’s daily.
That is why it has just been cataloged as the fastest growing black hole known in the universe, whose magnitude places it within the so-called «ultramassive black holes». “If our Milky Way’s black hole wanted to get so fat, it would have to swallow two-thirds of all the stars in our galaxy,” the astronomer said in a statement. Christopher Onken, from the National University of Australia in Australia, main author of a study on the subject in the journal “Monthly Notices of the Royal Astronomical Society”.
Known since 2018
The discovery of the giant in question it was first announced in 2018. This feeds a quasar at the center of a galaxy called SMSS J215728.21-360215.1 (J2157 for short) in the early Universe, billions of light-years away. At the beginning of its discovery, its mass was estimated at about 20,000 million solar masses, placing it in the ultramassive category (more than 10 billion solar masses), and its accretion rate (its growth) at half a daily solar mass.
But now, new measurements they indicate that astronomers and astrophysicists had been timid in their predictions. In its newly derived mass, the black hole J2157 would have a Schwarzschild radius – that is, the radius of its event horizon – of about 670 astronomical units (AU). Knowing that up to Pluto there would be a distance of 39.5 AU from the Sun, it can be said that J2157 has more than five times the size of the solar system.
And it’s not the biggest
Despite these incredible data, J2157 not the largest hole discovered for humanity: One of 40 billion solar masses is located in the heart of the Holmber 15A galaxy, some 700 million light years away. But we also have the ultramassive black hole that feeds the quasar TON 618, an absolute beast with 66,000 million solar masses 10.4 billion light-years away.
The supermassive black holes son difficult to understandBut the ultramassive ones hold even more mysteries if possible. The mechanism that forms both types of monsters is not very well known, nor how they grow so much. But J2157, which was formed when the Universe was less than 10% of its current age, belongs to a class of its own. Not only is the origin of its formation unknown, but it is not known how it could grow so much so close to the moment of the Big Bang. “It is the largest black hole in this early period of the Universe,” says Onken.
Supermassive black holes common at the beginning of the Universe?
However, recent studies point out that quasars that host supermassive black holes not only existed in the early Universe, but would have been quite common. This discovery is a great challenge for our current cosmological models, since according to these theories, an object like J2157 should have devoured a lot of matter in a long time, and with them calculations don’t add up. That is, on paper, there was not so much «food» for this giant to grow so much in such a short time. «Is this galaxy one of the giants of the early Universe, or the black hole swallowed an extraordinary amount of matter from the surroundings? Onken asks himself. “We will have to continue investigating to find out.”