Finding may explain how giant black holes appear – 08/20/2023 – Sidereal Messenger

We’ve known for a long time that virtually every galaxy has a giant, supermassive black hole at its center. The really tough question about them is how they formed. And now a new find, made with the help of the Chandra X-ray and James Webb infrared space telescopes, may begin to shed light on the mystery. In essence, the researchers found what may be a baby version of these intriguing objects.

It would be located in the heart of the galaxy UHZ1, whose light took 13.3 billion years to reach us – revealing what this object was like just 450 million years after the Big Bang. Two surprises came with it: first, a black hole already so huge, with an estimated mass of 40 million suns, so little time after the birth of the Universe; second, the fact that the galaxy itself is proportionally very modest, with an amount of mass gathered in its stars comparable to that of the central black hole itself, which seems to be voraciously consuming matter. It is a very different scenario from mature galaxies, such as the Milky Way, in which the central black hole accounts for about 0.1% of the mass that is distributed in stars.

This combination of factors is very important. That’s because the main hypothesis for the formation of these giant black holes is that they would be born from high-mass stars. After exhausting their fuel and collapsing, they would be converted into stellar black holes, with 10 to 100 solar masses, which would collide with each other over cosmic time until forming a massive object, adding millions or billions of suns in total mass.

The idea, however, stands in stark contrast to the existence of this distant object, which would not have had enough time since the Big Bang to gather so much mass. On the other hand, UHZ1 aligns very well with a less popular premise: that supermassive black holes are born big. According to the models that support this hypothesis, black holes of up to 100,000 solar masses could be born all at once, from the direct collapse of a gas cloud. That is, instead of this material fragmenting to form several stars, it would be all compressed in such a way that it would form a direct black hole, and a big one. In a short time (up to 5 million years), other stellar black holes formed around it would join, producing a “baby” supermassive black hole. If this is correct, then many objects of this category are expected to be found in the depths of space (thus in the early Universe). The researchers suggest that UHZ1 may have been the first. An important next step to confirm this, in addition to continuing to study this object in more detail, is to expand the search for other similar specimens.

The work describing the characteristics of the UHZ1 galaxy, which is led by Akos Bogdán, from Harvard University, in the USA, and also involves researchers from Princeton, Miami and Yale, was submitted for publication in the Astrophysical Journal Letters.

This column is published on Mondays in the printed version, in Folha Corrida.

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